diff --git a/src/list.c b/src/list.c
new file mode 100644
index 0000000..c64d039
--- /dev/null
+++ b/src/list.c
@@ -0,0 +1,412 @@
+/*
+ * Copyright (c) 2017 Bailey Thompson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <memory.h>
+#include <errno.h>
+#include "list.h"
+
+struct _list {
+    size_t data_size;
+    int space;
+    struct node *head;
+    struct node *tail;
+};
+
+struct node {
+    struct node *prev;
+    void *data;
+    struct node *next;
+};
+
+/**
+ * Initializes a doubly-linked list.
+ *
+ * @param data_size The size of data to store.
+ *
+ * @return The doubly-linked list, or NULL could not allocate memory.
+ */
+list list_init(const size_t data_size) {
+    struct _list *const init = malloc(sizeof(struct _list));
+    if (init == NULL) {
+        return NULL;
+    }
+    init->data_size = data_size;
+    init->space = 0;
+    init->head = NULL;
+    init->tail = NULL;
+    return init;
+}
+
+/**
+ * Gets the amount of elements in the doubly-linked list.
+ *
+ * @param me The doubly-linked list to check.
+ *
+ * @return The amount of elements.
+ */
+int list_size(list me) {
+    return me->space;
+}
+
+/**
+ * Determines if the doubly-linked list is empty.
+ *
+ * @param me The doubly-linked list to check.
+ *
+ * @return If the list is empty.
+ */
+bool list_is_empty(list me) {
+    return list_size(me) == 0;
+}
+
+/**
+ * Copies the nodes of the doubly-linked list to an array.
+ *
+ * @param array The array to copy the list to.
+ * @param me    The list to copy to the array.
+ */
+void list_to_array(void *const array, list me) {
+    struct node *traverse = me->head;
+    int offset = 0;
+    while (traverse != NULL) {
+        memcpy(array + offset, traverse->data, me->data_size);
+        offset += me->data_size;
+        traverse = traverse->next;
+    }
+}
+
+/*
+ * Get the node at index starting from the head.
+ */
+static struct node *get_node_from_head(list me, const int index) {
+    struct node *traverse = me->head;
+    for (int i = 0; i < index; i++) {
+        traverse = traverse->next;
+    }
+    return traverse;
+}
+
+/*
+ * Get the node at index starting from tail.
+ */
+static struct node *get_node_from_tail(list me, const int index) {
+    struct node *traverse = me->tail;
+    for (int i = me->space - 1; i > index; i--) {
+        traverse = traverse->prev;
+    }
+    return traverse;
+}
+
+/*
+ * Get the node at the specified index.
+ */
+static struct node *get_node_at(list me, const int index) {
+    if (index <= me->space / 2) {
+        return get_node_from_head(me, index);
+    } else {
+        return get_node_from_tail(me, index);
+    }
+}
+
+/**
+ * Adds data at the first index in the doubly-linked list.
+ *
+ * @param me   The list to add data to.
+ * @param data The data to add to the list.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
+ */
+int list_add_first(list me, void *const data) {
+    struct node *const traverse = me->head;
+    struct node *const add = malloc(sizeof(struct node));
+    if (add == NULL) {
+        return -ENOMEM;
+    }
+    add->data = malloc(me->data_size);
+    if (add->data == NULL) {
+        free(add);
+        return -ENOMEM;
+    }
+    add->prev = NULL;
+    memcpy(add->data, data, me->data_size);
+    add->next = traverse;
+    if (traverse != NULL) {
+        traverse->prev = add;
+    }
+    me->head = add;
+    if (me->tail == NULL) {
+        me->tail = traverse;
+    }
+    me->space++;
+    return 0;
+}
+
+/**
+ * Adds data at a specified index in the doubly-linked list.
+ *
+ * @param me    The list to add data to.
+ * @param index The index to add the data at.
+ * @param data  The data to add to the list.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
+ *         -EINVAL Invalid parameter.
+ */
+int list_add_at(list me, const int index, void *const data) {
+    if (index < 0 || index > me->space) {
+        return -EINVAL;
+    }
+    if (index == 0) {
+        return list_add_first(me, data);
+    }
+    if (index == me->space) {
+        return list_add_last(me, data);
+    }
+    // The new node will go right before this node.
+    struct node *const traverse = get_node_at(me, index);
+    struct node *const add = malloc(sizeof(struct node));
+    if (add == NULL) {
+        return -ENOMEM;
+    }
+    add->data = malloc(me->data_size);
+    if (add->data == NULL) {
+        free(add);
+        return -ENOMEM;
+    }
+    add->prev = traverse->prev;
+    memcpy(add->data, data, me->data_size);
+    add->next = traverse;
+    traverse->prev->next = add;
+    traverse->prev = add;
+    me->space++;
+    return 0;
+}
+
+/**
+ * Adds data at the last index in the doubly-linked list.
+ *
+ * @param me   The list to add data to.
+ * @param data The data to add to the list.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
+ */
+int list_add_last(list me, void *const data) {
+    struct node *const traverse = me->tail;
+    struct node *const add = malloc(sizeof(struct node));
+    if (add == NULL) {
+        return -ENOMEM;
+    }
+    add->data = malloc(me->data_size);
+    if (add->data == NULL) {
+        free(add);
+        return -ENOMEM;
+    }
+    add->prev = traverse;
+    memcpy(add->data, data, me->data_size);
+    add->next = NULL;
+    if (traverse != NULL) {
+        traverse->next = add;
+    }
+    me->tail = add;
+    me->space++;
+    return 0;
+}
+
+static bool isIllegalParameters(list me, const int index) {
+    return index < 0 || index >= me->space || me->space == 0;
+}
+
+/**
+ * Removes the first piece of data from the doubly-linked list.
+ *
+ * @param me The list to remove data from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_remove_first(list me) {
+    return list_remove_at(me, 0);
+}
+
+/**
+ * Removes data from the doubly-linked list at the specified index.
+ *
+ * @param me    The list to remove data from.
+ * @param index The index to remove from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_remove_at(list me, const int index) {
+    if (isIllegalParameters(me, index)) {
+        return -EINVAL;
+    }
+    struct node *const traverse = get_node_at(me, index);
+    if (index == 0) {
+        traverse->next->prev = NULL;
+        me->head = traverse->next;
+    } else if (index == me->space - 1) {
+        traverse->prev->next = NULL;
+        me->tail = traverse->prev;
+    } else {
+        traverse->prev->next = traverse->next;
+        traverse->next->prev = traverse->prev;
+    }
+    free(traverse);
+    me->space--;
+    return 0;
+}
+
+/**
+ * Removes the last piece of data from the doubly-linked list.
+ *
+ * @param me The list to remove data from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_remove_last(list me) {
+    return list_remove_at(me, me->space - 1);
+}
+
+/**
+ * Sets the data at the first index in the doubly-linked list.
+ *
+ * @param me   The list to set data for.
+ * @param data The data to set in the list.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_set_first(list me, void *const data) {
+    return list_set_at(me, 0, data);
+}
+
+/**
+ * Sets the data at the specified index in the doubly-linked list.
+ *
+ * @param me    The list to set data for.
+ * @param index The index to set data in the list.
+ * @param data  The data to set in the list.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_set_at(list me, const int index, void *const data) {
+    if (isIllegalParameters(me, index)) {
+        return -EINVAL;
+    }
+    struct node *const traverse = get_node_at(me, index);
+    memcpy(traverse->data, data, me->data_size);
+    return 0;
+}
+
+/**
+ * Sets the data at the last index in the doubly-linked list.
+ *
+ * @param me   The list to set data for.
+ * @param data The data to set in the list.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_set_last(list me, void *const data) {
+    return list_set_at(me, me->space - 1, data);
+}
+
+/**
+ * Gets the data at the first index in the doubly-linked list.
+ *
+ * @param data The data to get.
+ * @param me   The list to get data from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_get_first(void *const data, list me) {
+    return list_get_at(data, me, 0);
+}
+
+/**
+ * Gets the data at the specified index in the doubly-linked list.
+ *
+ * @param data  The data to get.
+ * @param me    The list to get data from.
+ * @param index The index to get data from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_get_at(void *const data, list me, const int index) {
+    if (isIllegalParameters(me, index)) {
+        return -EINVAL;
+    }
+    struct node *const traverse = get_node_at(me, index);
+    memcpy(data, traverse->data, me->data_size);
+    return 0;
+}
+
+/**
+ * Gets the data at the last index in the doubly-linked list.
+ *
+ * @param data The data to get.
+ * @param me   The list to get data from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
+ */
+int list_get_last(void *const data, list me) {
+    return list_get_at(data, me, me->space - 1);
+}
+
+/**
+ * Clears all elements from the doubly-linked list.
+ *
+ * @param me The list to clear.
+ */
+void list_clear(list me) {
+    struct node *traverse = me->head;
+    while (traverse != NULL) {
+        struct node *const temp = traverse;
+        traverse = traverse->next;
+        free(temp);
+    }
+    me->head = NULL;
+    me->space = 0;
+    me->tail = NULL;
+}
+
+/**
+ * Destroys the doubly-linked list.
+ *
+ * @param me The list to destroy.
+ *
+ * @return NULL
+ */
+list list_destroy(list me) {
+    list_clear(me);
+    free(me);
+    return NULL;
+}
diff --git a/src/list.h b/src/list.h
new file mode 100644
index 0000000..254990f
--- /dev/null
+++ b/src/list.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2017 Bailey Thompson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CONTAINERS_LIST_H
+#define CONTAINERS_LIST_H
+
+#include <stdbool.h>
+
+typedef struct _list *list;
+
+// Starting
+list list_init(size_t data_size);
+// Utility
+int list_size(list me);
+bool list_is_empty(list me);
+void list_to_array(void *array, list me);
+// Adding
+int list_add_first(list me, void *data);
+int list_add_at(list me, int index, void *data);
+int list_add_last(list me, void *data);
+// Removing
+int list_remove_first(list me);
+int list_remove_at(list me, int index);
+int list_remove_last(list me);
+// Setting
+int list_set_first(list me, void *data);
+int list_set_at(list me, int index, void *data);
+int list_set_last(list me, void *data);
+// Getting
+int list_get_first(void *data, list me);
+int list_get_at(void *data, list me, int index);
+int list_get_last(void *data, list me);
+// Ending
+void list_clear(list me);
+list list_destroy(list me);
+
+#endif /* CONTAINERS_LIST_H */
diff --git a/src/vector.c b/src/vector.c
index fe8e77b..bbea7aa 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -73,7 +73,7 @@ int vector_size(vector me) {
  *
  * @param me The vector to check.
  *
- * @return True if the vector is empty, else false.
+ * @return If the vector is empty.
  */
 bool vector_is_empty(vector me) {
     return vector_size(me) == 0;
@@ -197,6 +197,10 @@ int vector_add_last(vector me, void *const data) {
     return vector_add_at(me, me->offset, data);
 }
 
+static bool isIllegalParameters(vector me, const int index) {
+    return index < 0 || index >= me->offset || me->offset == 0;
+}
+
 /**
  * Removes the first element from the vector.
  *
@@ -219,7 +223,7 @@ int vector_remove_first(vector me) {
  *         -EINVAL Invalid parameter.
  */
 int vector_remove_at(vector me, const int index) {
-    if (index < 0 || index >= me->offset || me->offset == 0) {
+    if (isIllegalParameters(me, index)) {
         return -EINVAL;
     }
     memmove(me->storage + index * me->data_size,
@@ -249,9 +253,12 @@ int vector_remove_last(vector me) {
  * Sets the data for the first element in the vector.
  *
  * @param me The vector to set data for.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
  */
-void vector_set_first(vector me, void *const data) {
-    vector_set_at(me, 0, data);
+int vector_set_first(vector me, void *const data) {
+    return vector_set_at(me, 0, data);
 }
 
 /**
@@ -264,7 +271,7 @@ void vector_set_first(vector me, void *const data) {
  *         -EINVAL Invalid parameter.
  */
 int vector_set_at(vector me, const int index, void *const data) {
-    if (index < 0 || index >= me->offset) {
+    if (isIllegalParameters(me, index)) {
         return -EINVAL;
     }
     memcpy(me->storage + index * me->data_size, data, me->data_size);
@@ -275,9 +282,12 @@ int vector_set_at(vector me, const int index, void *const data) {
  * Sets the data for the last element in the vector.
  *
  * @param me The vector to set data for.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
  */
-void vector_set_last(vector me, void *const data) {
-    vector_set_at(me, me->offset - 1, data);
+int vector_set_last(vector me, void *const data) {
+    return vector_set_at(me, me->offset - 1, data);
 }
 
 /**
@@ -285,9 +295,12 @@ void vector_set_last(vector me, void *const data) {
  *
  * @param data The data to copy to.
  * @param me   The vector to copy from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
  */
-void vector_get_first(void *const data, vector me) {
-    vector_get_at(data, me, 0);
+int vector_get_first(void *const data, vector me) {
+    return vector_get_at(data, me, 0);
 }
 
 /**
@@ -301,7 +314,7 @@ void vector_get_first(void *const data, vector me) {
  *         -EINVAL Invalid parameter.
  */
 int vector_get_at(void *const data, vector me, const int index) {
-    if (index < 0 || index >= me->offset) {
+    if (isIllegalParameters(me, index)) {
         return -EINVAL;
     }
     memcpy(data, me->storage + index * me->data_size, me->data_size);
@@ -313,9 +326,12 @@ int vector_get_at(void *const data, vector me, const int index) {
  *
  * @param data The data to copy to.
  * @param me   The vector to copy from.
+ *
+ * @return 0       No error.
+ *         -EINVAL Invalid parameter.
  */
-void vector_get_last(void *const data, vector me) {
-    vector_get_at(data, me, me->offset - 1);
+int vector_get_last(void *const data, vector me) {
+    return vector_get_at(data, me, me->offset - 1);
 }
 
 /**
diff --git a/src/vector.h b/src/vector.h
index d9937a8..cb9a4a7 100644
--- a/src/vector.h
+++ b/src/vector.h
@@ -45,13 +45,13 @@ int vector_remove_first(vector me);
 int vector_remove_at(vector me, int index);
 int vector_remove_last(vector me);
 // Setting
-void vector_set_first(vector me, void *data);
+int vector_set_first(vector me, void *data);
 int vector_set_at(vector me, int index, void *data);
-void vector_set_last(vector me, void *data);
+int vector_set_last(vector me, void *data);
 // Getting
-void vector_get_first(void *data, vector me);
+int vector_get_first(void *data, vector me);
 int vector_get_at(void *data, vector me, int index);
-void vector_get_last(void *data, vector me);
+int vector_get_last(void *data, vector me);
 // Ending
 int vector_clear(vector me);
 vector vector_destroy(vector me);
diff --git a/tst/test.c b/tst/test.c
index d56bf38..d0dc3f1 100644
--- a/tst/test.c
+++ b/tst/test.c
@@ -2,6 +2,7 @@
 #include <errno.h>
 #include <assert.h>
 #include "../src/vector.h"
+#include "../src/list.h"
 
 static void test_vector(void) {
     int val[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
@@ -117,6 +118,120 @@ static void test_vector(void) {
     assert(me == NULL);
 }
 
-int main() {
-    test_vector();
+static void test_list(void) {
+    int val[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
+    list me = list_init(sizeof(int));
+    assert(me != NULL);
+    assert(list_size(me) == 0);
+    assert(list_is_empty(me));
+    for (int i = 0; i < 10; i++) {
+        list_add_first(me, &val[i]);
+        assert(list_size(me) == i + 1);
+        int get = 0;
+        list_get_first(&get, me);
+        assert(get == val[i]);
+    }
+    assert(list_size(me) == 10);
+    assert(!list_is_empty(me));
+    int get_arr[10] = {0};
+    list_to_array(get_arr, me);
+    for (int i = 0; i < 10; i++) {
+        int get = 0;
+        list_get_at(&get, me, i);
+        assert(get == val[9 - i]);
+        assert(get_arr[i] == val[9 - i]);
+    }
+    for (int i = 0; i < 7; i++) {
+        list_remove_last(me);
+    }
+    int trimmed[5] = {0};
+    list_to_array(trimmed, me);
+    assert(list_size(me) == 3);
+    for (int i = 0; i < 3; i++) {
+        assert(10 - i == trimmed[i]);
+    }
+    int add = 3;
+    list_add_last(me, &add);
+    add = -1;
+    list_add_at(me, 1, &add);
+    add = -2;
+    list_add_last(me, &add);
+    assert(list_size(me) == 6);
+    int aa = 456;
+    int a = 456;
+    int b = 456;
+    int c = 456;
+    int d = 456;
+    int e = 456;
+    int f = 456;
+    int ff = 456;
+    list_get_first(&aa, me);
+    assert(aa == 10);
+    list_get_at(&a, me, 0);
+    assert(a == 10);
+    list_get_at(&b, me, 1);
+    assert(b == -1);
+    list_get_at(&c, me, 2);
+    assert(c == 9);
+    list_get_at(&d, me, 3);
+    assert(d == 8);
+    list_get_at(&e, me, 4);
+    assert(e == 3);
+    list_get_at(&f, me, 5);
+    assert(f == -2);
+    list_get_last(&ff, me);
+    assert(ff == -2);
+    list_remove_first(me);
+    list_remove_at(me, 2);
+    list_remove_last(me);
+    assert(list_size(me) == 3);
+    int get = 345;
+    list_get_first(&get, me);
+    assert(get == -1);
+    list_get_at(&get, me, 1);
+    assert(get == 9);
+    list_get_last(&get, me);
+    assert(get == 3);
+    int set = 12;
+    list_set_first(me, &set);
+    set = 13;
+    list_set_at(me, 1, &set);
+    set = 14;
+    list_set_last(me, &set);
+    int arr[3] = {0};
+    list_to_array(arr, me);
+    assert(arr[0] == 12);
+    assert(arr[1] == 13);
+    assert(arr[2] == 14);
+    set = -5;
+    list_set_at(me, 0, &set);
+    set = -6;
+    list_set_at(me, 1, &set);
+    set = -7;
+    list_set_at(me, 2, &set);
+    list_to_array(arr, me);
+    assert(arr[0] == -5);
+    assert(arr[1] == -6);
+    assert(arr[2] == -7);
+    assert(list_set_at(me, 4, &set) == -EINVAL);
+    assert(list_get_at(&set, me, 4) == -EINVAL);
+    assert(list_remove_at(me, 4) == -EINVAL);
+    assert(list_add_at(me, 5, &set) == -EINVAL);
+    assert(list_set_at(me, -1, &set) == -EINVAL);
+    assert(list_get_at(&set, me, -1) == -EINVAL);
+    assert(list_remove_at(me, -1) == -EINVAL);
+    assert(list_add_at(me, -1, &set) == -EINVAL);
+    list_clear(me);
+    assert(list_size(me) == 0);
+    assert(list_is_empty(me));
+    assert(list_remove_first(me) == -EINVAL);
+    assert(list_remove_last(me) == -EINVAL);
+    me = list_destroy(me);
+    assert(me == NULL);
+}
+
+int main() {
+    //test_vector();
+    test_list();
+    return 0;
 }