diff --git a/src/main/java/me/braydon/feather/annotation/Serializable.java b/src/main/java/me/braydon/feather/annotation/Serializable.java
new file mode 100644
index 0000000..c05d552
--- /dev/null
+++ b/src/main/java/me/braydon/feather/annotation/Serializable.java
@@ -0,0 +1,11 @@
+package me.braydon.feather.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @author Braydon
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.FIELD)
+@Documented @Inherited
+public @interface Serializable { }
\ No newline at end of file
diff --git a/src/main/java/me/braydon/feather/common/Tuple.java b/src/main/java/me/braydon/feather/common/Tuple.java
new file mode 100644
index 0000000..c6085dd
--- /dev/null
+++ b/src/main/java/me/braydon/feather/common/Tuple.java
@@ -0,0 +1,25 @@
+package me.braydon.feather.common;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+/**
+ * Represents an object that
+ * holds a pair of two values.
+ *
+ * @author Braydon
+ */
+@NoArgsConstructor @AllArgsConstructor @Setter @Getter
+public class Tuple<L, R> {
+    /**
+     * The left value of this tuple.
+     */
+    private L left;
+    
+    /**
+     * The right value of this tuple.
+     */
+    private R right;
+}
\ No newline at end of file
diff --git a/src/main/java/me/braydon/feather/data/Document.java b/src/main/java/me/braydon/feather/data/Document.java
index c377fb0..0a4221f 100644
--- a/src/main/java/me/braydon/feather/data/Document.java
+++ b/src/main/java/me/braydon/feather/data/Document.java
@@ -8,11 +8,10 @@ import me.braydon.feather.IDatabase;
 import me.braydon.feather.annotation.Collection;
 import me.braydon.feather.annotation.Field;
 import me.braydon.feather.annotation.Id;
+import me.braydon.feather.annotation.Serializable;
+import me.braydon.feather.common.Tuple;
 
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.UUID;
+import java.util.*;
 
 /**
  * A document is a key-value pair that is stored
@@ -38,12 +37,18 @@ public class Document<V> {
     
     /**
      * The mapped data of this document.
+     * <p>
+     * The key of this key-value pair is the identifier
+     * for the field within this document. The value is
+     * a tuple that contains the Java field, as well as
+     * the field value.
+     * </p>
      *
      * @see V for value type
      */
-    private final Map<String, V> mappedData = Collections.synchronizedMap(new LinkedHashMap<>());
+    private final Map<String, Tuple<java.lang.reflect.Field, V>> mappedData = Collections.synchronizedMap(new LinkedHashMap<>());
     
-    public Document(@NonNull Object element, boolean rawObject) {
+    public Document(@NonNull Object element) {
         Class<?> clazz = element.getClass(); // Get the element class
         String idKey = null; // The key for the id field
         for (java.lang.reflect.Field field : clazz.getDeclaredFields()) {
@@ -64,20 +69,15 @@ public class Document<V> {
             }
             Class<?> fieldType = field.getType(); // The type of the field
             try {
-                Object value; // The value of the field
+                Object value = field.get(element); // The value of the field
                 
-                if (fieldType == UUID.class) { // Convert UUIDs into strings
-                    value = ((UUID) field.get(element)).toString();
-                } else if (rawObject) { // Use the raw object from the field
-                    value = field.get(element);
-                } else { // Otherwise, turn the value into a string
-                    if (fieldType == String.class) { // Already a string, cast it
-                        value = field.get(element);
-                    } else { // Convert the field into json using Gson
-                        value = FeatherSettings.getGson().toJson(field.get(element));
-                    }
+                if (field.isAnnotationPresent(Serializable.class)) { // Serialize the field if @Serializable is present
+                    value = FeatherSettings.getGson().toJson(field.get(element));
+                } else if (fieldType == UUID.class) { // Convert UUIDs into strings
+                    value = ((UUID) value).toString();
                 }
-                mappedData.put(key, (V) value); // Store in our map
+                
+                mappedData.put(key, new Tuple<>(field, (V) value)); // Store in our map
             } catch (IllegalAccessException ex) {
                 throw new RuntimeException(ex);
             }
@@ -85,10 +85,25 @@ public class Document<V> {
         assert idKey != null; // We need an id key
         this.idKey = idKey; // We have our id key
         
-        V key = mappedData.get(idKey); // Get the id from the data map
+        Tuple<java.lang.reflect.Field, V> key = mappedData.get(idKey); // Get the id from the data map
         if (key == null) { // The element is missing an id field
             throw new IllegalArgumentException("No @Id annotated field found in " + clazz.getSimpleName());
         }
-        this.key = key;
+        this.key = key.getRight();
+    }
+    
+    /**
+     * Turn this document into a map.
+     *
+     * @return the mapped data
+     * @see #mappedData for stored data
+     */
+    @NonNull
+    public Map<String, V> toMappedData() {
+        Map<String, V> mappedData = new LinkedHashMap<>(); // The mapped data
+        for (Map.Entry<String, Tuple<java.lang.reflect.Field, V>> entry : this.mappedData.entrySet()) {
+            mappedData.put(entry.getKey(), entry.getValue().getRight());
+        }
+        return mappedData;
     }
 }
\ No newline at end of file
diff --git a/src/main/java/me/braydon/feather/databases/mongodb/MongoDB.java b/src/main/java/me/braydon/feather/databases/mongodb/MongoDB.java
index cbb4c17..1f56bca 100644
--- a/src/main/java/me/braydon/feather/databases/mongodb/MongoDB.java
+++ b/src/main/java/me/braydon/feather/databases/mongodb/MongoDB.java
@@ -6,13 +6,18 @@ import com.mongodb.client.MongoClients;
 import com.mongodb.client.MongoCollection;
 import com.mongodb.client.MongoDatabase;
 import com.mongodb.client.model.Filters;
+import com.mongodb.client.model.Indexes;
 import com.mongodb.client.model.UpdateOptions;
 import lombok.Getter;
 import lombok.NonNull;
 import me.braydon.feather.IDatabase;
 import me.braydon.feather.annotation.Collection;
 import me.braydon.feather.annotation.Field;
+import me.braydon.feather.common.Tuple;
 import me.braydon.feather.data.Document;
+import me.braydon.feather.databases.mongodb.annotation.Index;
+
+import java.util.Map;
 
 /**
  * The {@link IDatabase} implementation for MongoDB.
@@ -137,14 +142,22 @@ public class MongoDB implements IDatabase<MongoClient, ConnectionString, MongoSy
             throw new IllegalStateException("Missing collection name in @Collection for " + clazz.getSimpleName());
         }
         MongoCollection<org.bson.Document> collection = database.getCollection(collectionName); // Get the collection
-        Document<Object> document = new Document<>(element, true); // Construct the document from the element
+        Document<Object> document = new Document<>(element); // Construct the document from the element
         
         // Set the map in the database
         collection.updateOne(
             Filters.eq(document.getIdKey(), document.getKey()),
-            new org.bson.Document("$set", new org.bson.Document(document.getMappedData())),
+            new org.bson.Document("$set", new org.bson.Document(document.toMappedData())),
             new UpdateOptions().upsert(true)
         );
+        
+        // Create indexes for @Index fields
+        for (Map.Entry<String, Tuple<java.lang.reflect.Field, Object>> entry : document.getMappedData().entrySet()) {
+            java.lang.reflect.Field field = entry.getValue().getLeft();
+            if (field.isAnnotationPresent(Index.class)) {
+                collection.createIndex(Indexes.text(entry.getKey()));
+            }
+        }
     }
     
     /**
diff --git a/src/main/java/me/braydon/feather/databases/mongodb/annotation/Index.java b/src/main/java/me/braydon/feather/databases/mongodb/annotation/Index.java
new file mode 100644
index 0000000..1a6bba4
--- /dev/null
+++ b/src/main/java/me/braydon/feather/databases/mongodb/annotation/Index.java
@@ -0,0 +1,16 @@
+package me.braydon.feather.databases.mongodb.annotation;
+
+import me.braydon.feather.databases.mongodb.MongoDB;
+
+import java.lang.annotation.*;
+
+/**
+ * Fields flagged with this annotation will be
+ * treated as an indexed field within {@link MongoDB}.
+ *
+ * @author Braydon
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.FIELD)
+@Documented @Inherited
+public @interface Index { }
\ No newline at end of file
diff --git a/src/main/java/me/braydon/feather/databases/redis/Redis.java b/src/main/java/me/braydon/feather/databases/redis/Redis.java
index 70936de..8e1bd99 100644
--- a/src/main/java/me/braydon/feather/databases/redis/Redis.java
+++ b/src/main/java/me/braydon/feather/databases/redis/Redis.java
@@ -126,8 +126,8 @@ public class Redis implements IDatabase<StatefulRedisConnection<String, String>,
         if (!element.getClass().isAnnotationPresent(Collection.class)) { // Missing annotation
             throw new IllegalStateException("Element is missing @Collection annotation");
         }
-        Document<String> document = new Document<>(element, false); // Construct the document from the element
-        sync().hmset(String.valueOf(document.getKey()), document.getMappedData()); // Set the map in the database
+        Document<String> document = new Document<>(element); // Construct the document from the element
+        sync().hmset(String.valueOf(document.getKey()), document.toMappedData()); // Set the map in the database
     }
     
     /**
diff --git a/src/main/java/me/braydon/feather/repository/Repository.java b/src/main/java/me/braydon/feather/repository/Repository.java
index f757fd7..4251009 100644
--- a/src/main/java/me/braydon/feather/repository/Repository.java
+++ b/src/main/java/me/braydon/feather/repository/Repository.java
@@ -20,4 +20,13 @@ public abstract class Repository<D extends IDatabase<?, ?, ?, ?>> {
      * @see D for database
      */
     @NonNull private final D database;
+    
+    /**
+     * Save the given element to the database.
+     *
+     * @param element the element to save
+     */
+    public final void save(@NonNull Object element) {
+        database.write(element);
+    }
 }
\ No newline at end of file