diff --git a/src/priority_queue.c b/src/priority_queue.c
new file mode 100644
index 0000000..a482f06
--- /dev/null
+++ b/src/priority_queue.c
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2017-2018 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 "vector.h"
+#include "priority_queue.h"
+
+/*
+ * Must exactly match the declaration in vector.c
+ */
+struct _vector {
+    size_t data_size;
+    int offset;
+    int space;
+    void *storage;
+};
+
+struct _priority_queue {
+    vector data;
+    size_t data_size;
+    int (*comparator)(const void *const one, const void *const two);
+};
+
+/**
+ * Initializes a priority queue, which adapts a container to provide priority
+ * queue. Adapts the vector container.
+ *
+ * @param data_size  The size of the data in the priority queue.
+ * @param comparator The priority comparator function.
+ *
+ * @return The newly-initialized priority queue, or NULL if memory allocation
+ *         error.
+ */
+priority_queue priority_queue_init(const size_t data_size,
+                                   int (*comparator)(const void *const,
+                                                     const void *const))
+{
+    struct _priority_queue *const init = malloc(sizeof(struct _priority_queue));
+    if (init == NULL) {
+        return NULL;
+    }
+    init->data_size = data_size;
+    init->data = vector_init(data_size);
+    if (init->data == NULL) {
+        free(init);
+        return NULL;
+    }
+    init->comparator = comparator;
+    return init;
+}
+
+/**
+ * Gets the size of the priority queue.
+ *
+ * @param me The priority queue to check.
+ *
+ * @return The size of the priority queue.
+ */
+int priority_queue_size(priority_queue me)
+{
+    return vector_size(me->data);
+}
+
+/**
+ * Determines whether or not the priority queue is empty.
+ *
+ * @param me The priority queue to check.
+ *
+ * @return If the priority queue is empty.
+ */
+bool priority_queue_is_empty(priority_queue me)
+{
+    return vector_is_empty(me->data);
+}
+
+/**
+ * Adds an element to the priority queue.
+ *
+ * @param me   The priority queue to add an element to.
+ * @param data The data to add to the queue.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
+ */
+int priority_queue_push(priority_queue me, void *const data)
+{
+    void *const temp = malloc(me->data_size);
+    if (temp == NULL) {
+        return -ENOMEM;
+    }
+    const int rc = vector_add_last(me->data, data);
+    if (rc != 0) {
+        free(temp);
+        return rc;
+    }
+    void *const vector_storage = me->data->storage;
+    int index = vector_size(me->data) - 1;
+    int parent_index = (index - 1) / 2;
+    void *data_index = vector_storage + index * me->data_size;
+    void *data_parent_index = vector_storage + parent_index * me->data_size;
+    while (index > 0 && me->comparator(data_index, data_parent_index) > 0) {
+        memcpy(temp, data_parent_index, me->data_size);
+        memcpy(data_parent_index, data_index, me->data_size);
+        memcpy(data_index, temp, me->data_size);
+        index = parent_index;
+        parent_index = (index - 1) / 2;
+        data_index = vector_storage + index * me->data_size;
+        data_parent_index = vector_storage + parent_index * me->data_size;
+    }
+    free(temp);
+    return 0;
+}
+
+/**
+ * Removes the highest priority element from the priority queue.
+ *
+ * @param data The data to have copied from the priority queue.
+ * @param me   The priority queue to pop the next element from.
+ *
+ * @return If the priority queue contained elements.
+ */
+bool priority_queue_pop(void *const data, priority_queue me)
+{
+    const int rc = vector_get_first(data, me->data);
+    if (rc != 0) {
+        return false;
+    }
+    void *const vector_storage = me->data->storage;
+    const int size = vector_size(me->data) - 1;
+    void *const temp = vector_storage + size * me->data_size;
+    memcpy(vector_storage, temp, me->data_size);
+    int index = 0;
+    int left_index = 1;
+    int right_index = 2;
+    void *data_index = vector_storage;
+    void *data_left_index = vector_storage + left_index * me->data_size;
+    void *data_right_index = vector_storage + right_index * me->data_size;
+    while (true) {
+        if (right_index < size &&
+            me->comparator(data_right_index, data_left_index) > 0 &&
+            me->comparator(data_right_index, data_index) > 0) {
+            // Swap parent and right child then continue down right child.
+            memcpy(temp, data_index, me->data_size);
+            memcpy(data_index, data_right_index, me->data_size);
+            memcpy(data_right_index, temp, me->data_size);
+            index = right_index;
+        } else if (left_index < size &&
+                   me->comparator(data_left_index, data_index) > 0) {
+            // Swap parent and left child then continue down left child.
+            memcpy(temp, data_index, me->data_size);
+            memcpy(data_index, data_left_index, me->data_size);
+            memcpy(data_left_index, temp, me->data_size);
+            index = left_index;
+        } else {
+            break;
+        }
+        left_index = 2 * index + 1;
+        right_index = 2 * index + 2;
+        data_index = vector_storage + index * me->data_size;
+        data_left_index = vector_storage + left_index * me->data_size;
+        data_right_index = vector_storage + right_index * me->data_size;
+    }
+    vector_remove_last(me->data);
+    return true;
+}
+
+/**
+ * Gets the highest priority element in the priority queue.
+ *
+ * @param data Out copy of the highest priority element in the priority queue.
+ * @param me   The priority queue to copy from.
+ *
+ * @return If the priority queue contained elements.
+ */
+bool priority_queue_front(void *const data, priority_queue me)
+{
+    return vector_get_first(data, me->data) == 0;
+}
+
+/**
+ * Clears the elements from the priority queue.
+ *
+ * @param me The priority queue to clear.
+ *
+ * @return 0       No error.
+ *         -ENOMEM Out of memory.
+ */
+int priority_queue_clear(priority_queue me)
+{
+    return vector_clear(me->data);
+}
+
+/**
+ * Frees the priority queue memory.
+ *
+ * @param me The priority queue to free from memory.
+ *
+ * @return NULL
+ */
+priority_queue priority_queue_destroy(priority_queue me)
+{
+    vector_destroy(me->data);
+    free(me);
+    return NULL;
+}
diff --git a/src/priority_queue.h b/src/priority_queue.h
new file mode 100644
index 0000000..c3b6ef3
--- /dev/null
+++ b/src/priority_queue.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2017-2018 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_PRIORITY_QUEUE_H
+#define CONTAINERS_PRIORITY_QUEUE_H
+
+#include <stdbool.h>
+
+typedef struct _priority_queue *priority_queue;
+
+// Starting
+priority_queue priority_queue_init(size_t data_size,
+                                   int (*comparator)(const void *const one,
+                                                     const void *const two));
+
+// Utility
+int priority_queue_size(priority_queue me);
+bool priority_queue_is_empty(priority_queue me);
+
+// Adding
+int priority_queue_push(priority_queue me, void *data);
+
+// Removing
+bool priority_queue_pop(void *data, priority_queue me);
+
+// Getting
+bool priority_queue_front(void *data, priority_queue me);
+
+// Ending
+int priority_queue_clear(priority_queue me);
+priority_queue priority_queue_destroy(priority_queue me);
+
+#endif /* CONTAINERS_PRIORITY_QUEUE_H */
diff --git a/src/queue.c b/src/queue.c
index 14410ae..71ae9c8 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 Bailey Thompson
+ * Copyright (c) 2017-2018 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
@@ -32,8 +32,8 @@ struct _queue {
 };
 
 /**
- * Initializes a queue which is first-in first-out. Uses a deque as the
- * underlying implementation.
+ * Initializes a queue, which adapts a container to provide queue
+ * (first-in first-out). Adapts the deque container.
  *
  * @param data_size The size of each element.
  *
diff --git a/src/stack.c b/src/stack.c
index 36eea03..0a302cc 100644
--- a/src/stack.c
+++ b/src/stack.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 Bailey Thompson
+ * Copyright (c) 2017-2018 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
@@ -29,8 +29,8 @@ struct _stack {
 };
 
 /**
- * Initializes a stack which is last-in first-out. Uses a deque as the
- * underlying implementation.
+ * Initializes a stack, which adapts a container to provide stack
+ * (last-in first-out). Adapts the deque container.
  *
  * @param data_size The size of each data element in the stack.
  *
diff --git a/tst/priority_queue.c b/tst/priority_queue.c
new file mode 100644
index 0000000..d1c7bab
--- /dev/null
+++ b/tst/priority_queue.c
@@ -0,0 +1,131 @@
+#include "test.h"
+#include "../src/vector.h"
+#include "../src/priority_queue.h"
+
+/*
+ * Include this for the stubs.
+ */
+struct _vector {
+    size_t data_size;
+    int offset;
+    int space;
+    void *storage;
+};
+
+/*
+ * Include this for the stubs.
+ */
+struct _priority_queue {
+    vector data;
+    size_t data_size;
+    int (*comparator)(const void *const one, const void *const two);
+};
+
+static void priority_queue_verify(priority_queue me)
+{
+    void *const vector_storage = me->data->storage;
+    const int size = vector_size(me->data);
+    for (int i = 0; i < size; i++) {
+        const int val = *(int *) (vector_storage + i * me->data_size);
+        const int left_child = 2 * i + 1;
+        const int right_child = 2 * i + 2;
+        if (left_child < size) {
+            void *left_data = vector_storage + left_child * me->data_size;
+            const int left_val = *(int *) left_data;
+            assert(val >= left_val);
+        }
+        if (right_child < size) {
+            void *right_data = vector_storage + right_child * me->data_size;
+            const int right_val = *(int *) right_data;
+            assert(val >= right_val);
+        }
+    }
+}
+
+static int compare_int(const void *const one, const void *const two)
+{
+    const int a = *(int *) one;
+    const int b = *(int *) two;
+    return a - b;
+}
+
+int stub_priority_queue_push(priority_queue me, void *const data)
+{
+    const int ret = priority_queue_push(me, data);
+    priority_queue_verify(me);
+    return ret;
+}
+
+bool stub_priority_queue_pop(void *const data, priority_queue me)
+{
+    const bool ret = priority_queue_pop(data, me);
+    priority_queue_verify(me);
+    return ret;
+}
+
+void test_priority_queue(void)
+{
+    priority_queue a = priority_queue_init(sizeof(int), compare_int);
+    assert(a != NULL);
+    assert(priority_queue_size(a) == 0);
+    assert(priority_queue_is_empty(a));
+    int b = 5;
+    stub_priority_queue_push(a, &b);
+    b = 2;
+    stub_priority_queue_push(a, &b);
+    b = 7;
+    stub_priority_queue_push(a, &b);
+    b = 3;
+    stub_priority_queue_push(a, &b);
+    b = 4;
+    stub_priority_queue_push(a, &b);
+    b = 5;
+    stub_priority_queue_push(a, &b);
+    b = 9;
+    stub_priority_queue_push(a, &b);
+    b = 2;
+    stub_priority_queue_push(a, &b);
+    b = 3;
+    stub_priority_queue_push(a, &b);
+    b = -5;
+    stub_priority_queue_push(a, &b);
+    b = 7;
+    stub_priority_queue_push(a, &b);
+    b = 3;
+    stub_priority_queue_push(a, &b);
+    b = 4;
+    stub_priority_queue_push(a, &b);
+    b = 3;
+    stub_priority_queue_push(a, &b);
+    b = 11;
+    stub_priority_queue_push(a, &b);
+    b = 6;
+    stub_priority_queue_push(a, &b);
+    assert(priority_queue_size(a) == 16);
+    assert(!priority_queue_is_empty(a));
+    b = 0xdeadbeef;
+    priority_queue_front(&b, a);
+    assert(b == 11);
+    b = 0xdeadbeef;
+    stub_priority_queue_pop(&b, a);
+    assert(b == 11);
+    assert(priority_queue_size(a) == 15);
+    b = 0xdeadbeef;
+    priority_queue_front(&b, a);
+    assert(b == 9);
+    int c = b;
+    for (int i = 0; i < 15; i++) {
+        stub_priority_queue_pop(&b, a);
+        assert(b <= c);
+        c = b;
+        assert(priority_queue_size(a) == 15 - i - 1);
+    }
+    priority_queue_clear(a);
+    assert(priority_queue_is_empty(a));
+    b = 0xdeadbeef;
+    assert(!priority_queue_front(&b, a));
+    assert(b == 0xdeadbeef);
+    assert(priority_queue_is_empty(a));
+    a = priority_queue_destroy(a);
+    assert(a == NULL);
+}
diff --git a/tst/test.c b/tst/test.c
index c0d7ecf..937469b 100644
--- a/tst/test.c
+++ b/tst/test.c
@@ -17,5 +17,6 @@ int main(void)
     test_unordered_multimap();
     test_stack();
     test_queue();
+    test_priority_queue();
     return 0;
 }
diff --git a/tst/test.h b/tst/test.h
index 99add38..dbef271 100644
--- a/tst/test.h
+++ b/tst/test.h
@@ -20,5 +20,6 @@ void test_unordered_multiset(void);
 void test_unordered_multimap(void);
 void test_stack(void);
 void test_queue(void);
+void test_priority_queue(void);
 
 #endif /* CONTAINERS_TEST_H */