diff --git a/lib/glacier/container/hash_map.h b/lib/glacier/container/hash_map.h
new file mode 100644
index 0000000..1c066b4
--- /dev/null
+++ b/lib/glacier/container/hash_map.h
@@ -0,0 +1,222 @@
+#pragma once
+
+#include <stdint.h>
+
+#include "glacier/container/array.h"
+#include "glacier/container/linked_list.h"
+#include "glacier/container/pair.h"
+#include "glacier/status/error.h"
+
+namespace glcr {
+
+template <typename T>
+struct HashFunc {
+  uint64_t operator()(const T&);
+};
+
+template <>
+struct HashFunc<uint64_t> {
+  uint64_t operator()(const uint64_t& value) {
+    // FIXME: Write a real hash function.
+    return 0xABBAABBAABBAABBA ^ value;
+  }
+};
+
+template <typename K, typename V, class H = HashFunc<K>>
+class HashMap {
+ public:
+  HashMap() = default;
+  HashMap(const HashMap&) = delete;
+  HashMap& operator=(const HashMap&) = delete;
+  // TODO: Implement Move.
+  HashMap(HashMap&&) = delete;
+  HashMap& operator=(HashMap&&) = delete;
+
+  // Accessors.
+  uint64_t size() { return size_; }
+  uint64_t empty() { return size_ == 0; }
+
+  // Returns load as a percentage (i.e. 60 means the load is 0.6).
+  //
+  // If data is a zero-size array, return load as 100 so it will be flagged for
+  // resize.
+  // TODO: Return a double here once FPE is enabled.
+  uint64_t load() {
+    if (data_.size() == 0) {
+      return 100;
+    }
+    return size_ * 100 / data_.size();
+  }
+
+  V& at(const K&);
+  const V& at(const K&) const;
+
+  bool Contains(const K&) const;
+
+  // Setters.
+  [[nodiscard]] ErrorCode Insert(const K&, const V&);
+  [[nodiscard]] ErrorCode Insert(K&&, V&&);
+
+  [[nodiscard]] ErrorCode Update(const K&, const V&);
+  [[nodiscard]] ErrorCode Update(const K&, V&&);
+
+  [[nodiscard]] ErrorCode Delete(const K&);
+
+  void Resize(uint64_t new_size);
+
+ private:
+  Array<LinkedList<Pair<K, V>>> data_;
+  uint64_t size_ = 0;
+
+  void ResizeIfNecessary();
+};
+
+template <typename K, typename V, class H>
+V& HashMap<K, V, H>::at(const K& key) {
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      return pair.second();
+    }
+  }
+  // TODO: Add a failure mode here instead of constructing an object.
+  ll.PushFront({key, {}});
+  return ll.PeekFront().second();
+}
+
+template <typename K, typename V, class H>
+const V& HashMap<K, V, H>::at(const K& key) const {
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      return pair.second();
+    }
+  }
+  // TODO: Add a failure mode here instead of constructing an object.
+  ll.PushFront({key, {}});
+  return ll.PeekFront().second();
+}
+
+template <typename K, typename V, class H>
+bool HashMap<K, V, H>::Contains(const K& key) const {
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      return true;
+    }
+  }
+  return false;
+}
+
+template <typename K, typename V, class H>
+ErrorCode HashMap<K, V, H>::Insert(const K& key, const V& value) {
+  ResizeIfNecessary();
+
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      return ALREADY_EXISTS;
+    }
+  }
+  ll.PushFront({Move(key), Move(value)});
+  size_++;
+  return OK;
+}
+
+template <typename K, typename V, class H>
+ErrorCode HashMap<K, V, H>::Insert(K&& key, V&& value) {
+  ResizeIfNecessary();
+
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      return ALREADY_EXISTS;
+    }
+  }
+  ll.PushFront({Move(key), Move(value)});
+  size_++;
+  return OK;
+}
+
+template <typename K, typename V, class H>
+ErrorCode HashMap<K, V, H>::Update(const K& key, const V& value) {
+  ResizeIfNecessary();
+
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      pair.second() = value;
+      return OK;
+    }
+  }
+  return NOT_FOUND;
+}
+
+template <typename K, typename V, class H>
+ErrorCode HashMap<K, V, H>::Update(const K& key, V&& value) {
+  ResizeIfNecessary();
+
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      pair.second() = Move(value);
+      return OK;
+    }
+  }
+  return NOT_FOUND;
+}
+
+template <typename K, typename V, class H>
+ErrorCode HashMap<K, V, H>::Delete(const K& key) {
+  uint64_t hc = H()(key);
+  auto& ll = data_[hc % data_.size()];
+
+  for (auto& pair : ll) {
+    if (pair.first() == key) {
+      ll.Remove(pair);
+      size_--;
+      return OK;
+    }
+  }
+  return NOT_FOUND;
+}
+
+template <typename K, typename V, class H>
+void HashMap<K, V, H>::Resize(uint64_t new_size) {
+  Array<LinkedList<Pair<K, V>>> new_data(new_size);
+
+  for (uint64_t i = 0; i < data_.size(); i++) {
+    auto& ll = data_[i];
+    while (!ll.empty()) {
+      auto pair = ll.PopFront();
+      uint64_t hc = H()(pair.first());
+      new_data[hc % new_size].PushFront(Move(pair));
+    }
+  }
+  data_ = glcr::Move(new_data);
+}
+
+template <typename K, typename V, class H>
+void HashMap<K, V, H>::ResizeIfNecessary() {
+  if (data_.size() == 0) {
+    Resize(8);
+  } else if (load() > 75) {
+    Resize(data_.size() * 2);
+  }
+}
+
+}  // namespace glcr
diff --git a/lib/glacier/container/linked_list.h b/lib/glacier/container/linked_list.h
index e5fd24f..be1d2cc 100644
--- a/lib/glacier/container/linked_list.h
+++ b/lib/glacier/container/linked_list.h
@@ -23,6 +23,8 @@ class LinkedList {
 
   T PopFront();
 
+  void Remove(const T& item);
+
   void PushFront(const T& item);
   void PushFront(T&& item);
 
@@ -53,7 +55,9 @@ class LinkedList {
   };
 
   Iterator begin() { return {front_}; }
+  const Iterator begin() const { return {front_}; }
   Iterator end() { return {nullptr}; }
+  const Iterator end() const { return {nullptr}; }
 
  private:
   uint64_t size_ = 0;
@@ -123,4 +127,21 @@ T LinkedList<T>::PopFront() {
   return Move(ret);
 }
 
+template <typename T>
+void LinkedList<T>::Remove(const T& item) {
+  if (front_->item == item) {
+    PopFront();
+    return;
+  }
+  ListItem* iter = front_;
+  while (iter != nullptr) {
+    if (iter->next != nullptr && iter->next->item == item) {
+      iter->next = iter->next->next;
+      size_--;
+      return;
+    }
+    iter = iter->next;
+  }
+}
+
 }  // namespace glcr
diff --git a/lib/glacier/container/pair.h b/lib/glacier/container/pair.h
index e633fef..9ad2753 100644
--- a/lib/glacier/container/pair.h
+++ b/lib/glacier/container/pair.h
@@ -1,14 +1,23 @@
 #pragma once
 
+#include <stdint.h>
+
+#include "glacier/memory/move.h"
+
 namespace glcr {
 
 template <typename T, typename U>
 class Pair {
  public:
   Pair(const T& first, const U& second) : first_(first), second_(second) {}
+  Pair(T&& first, U&& second) : first_(Move(first)), second_(Move(second)) {}
   T& first() { return first_; }
   U& second() { return second_; }
 
+  bool operator==(const Pair& other) {
+    return other.first_ == first_ && other.second_ == second_;
+  }
+
  private:
   T first_;
   U second_;
diff --git a/zion/capability/capability_table.cpp b/zion/capability/capability_table.cpp
index babda9a..4725389 100644
--- a/zion/capability/capability_table.cpp
+++ b/zion/capability/capability_table.cpp
@@ -8,37 +8,26 @@ uint64_t CapabilityTable::AddExistingCapability(
     const glcr::RefPtr<Capability>& cap) {
   MutexHolder h(lock_);
   uint64_t id = next_cap_id_++;
-  capabilities_.PushBack({.id = id, .cap = cap});
+  if (capabilities_.Insert(id, cap) != glcr::OK) {
+    panic("Reusing capability id.");
+  }
   return id;
 }
 
 glcr::RefPtr<Capability> CapabilityTable::GetCapability(uint64_t id) {
   MutexHolder h(lock_);
-  auto iter = capabilities_.begin();
-  while (iter != capabilities_.end()) {
-    if (iter->cap && iter->id == id) {
-      return iter->cap;
-    }
-    ++iter;
+  if (!capabilities_.Contains(id)) {
+    panic("Bad cap access {}", id);
   }
-  dbgln("Bad cap access {}", id);
-  dbgln("Num caps: {}", capabilities_.size());
-  return {};
+  return capabilities_.at(id);
 }
 
 glcr::RefPtr<Capability> CapabilityTable::ReleaseCapability(uint64_t id) {
   MutexHolder h(lock_);
-  auto iter = capabilities_.begin();
-  while (iter != capabilities_.end()) {
-    if (iter->cap && iter->id == id) {
-      // FIXME: Do an actual release here.
-      auto cap = iter->cap;
-      iter->cap = {nullptr};
-      return cap;
-    }
-    ++iter;
+  if (!capabilities_.Contains(id)) {
+    panic("Bad cap release {}", id);
   }
-  dbgln("Bad cap release: {}", id);
-  dbgln("Num caps: {}", capabilities_.size());
-  return {};
+  auto cap = capabilities_.at(id);
+  (void)capabilities_.Delete(id);
+  return cap;
 }
diff --git a/zion/capability/capability_table.h b/zion/capability/capability_table.h
index 78cf85b..a67112c 100644
--- a/zion/capability/capability_table.h
+++ b/zion/capability/capability_table.h
@@ -1,9 +1,10 @@
 #pragma once
 
-#include <glacier/container/linked_list.h>
+#include <glacier/container/hash_map.h>
 #include <glacier/memory/ref_ptr.h>
 
 #include "capability/capability.h"
+#include "debug/debug.h"
 #include "object/mutex.h"
 
 class CapabilityTable {
@@ -28,12 +29,8 @@ class CapabilityTable {
   glcr::RefPtr<Mutex> lock_ = Mutex::Create();
   // TODO: Do some randomization.
   uint64_t next_cap_id_ = 0x100;
-  // FIXME: use a map data structure.
-  struct CapEntry {
-    uint64_t id;
-    glcr::RefPtr<Capability> cap;
-  };
-  glcr::LinkedList<CapEntry> capabilities_;
+  // TODO: Consider not holding a uniqueptr here instead of a refptr?
+  glcr::HashMap<uint64_t, glcr::RefPtr<Capability>> capabilities_;
 };
 
 template <typename T>
@@ -41,7 +38,9 @@ uint64_t CapabilityTable::AddNewCapability(const glcr::RefPtr<T>& object,
                                            uint64_t permissions) {
   MutexHolder h(lock_);
   uint64_t id = next_cap_id_++;
-  capabilities_.PushBack(
-      {.id = id, .cap = MakeRefCounted<Capability>(object, permissions)});
+  if (capabilities_.Insert(
+          id, MakeRefCounted<Capability>(object, permissions)) != glcr::OK) {
+    panic("Reusing capability id {}", id);
+  }
   return id;
 }