diff --git a/src/main/java/envoy/server/Startup.java b/src/main/java/envoy/server/Startup.java
index 8ccbe5e..e23bf69 100644
--- a/src/main/java/envoy/server/Startup.java
+++ b/src/main/java/envoy/server/Startup.java
@@ -38,6 +38,8 @@ public class Startup {
 		processors.add(new MessageStatusChangeProcessor());
 		processors.add(new UserStatusChangeProcessor());
 		processors.add(new IdGeneratorRequestProcessor());
+		processors.add(new ContactsRequestEventProcessor());
+		processors.add(new ContactOperationProcessor());
 		Server server = new Server(8080, () -> new ObjectMessageReader(), new ObjectMessageProcessor(processors));
 
 		initializeCurrentMessageId();
diff --git a/src/main/java/envoy/server/data/User.java b/src/main/java/envoy/server/data/User.java
index 7b9cbd7..4cee18e 100644
--- a/src/main/java/envoy/server/data/User.java
+++ b/src/main/java/envoy/server/data/User.java
@@ -16,14 +16,19 @@ import javax.persistence.*;
  * Created: <strong>02.01.2020</strong><br>
  *
  * @author Kai S. K. Engelbart
+ * @author Maximilian K&auml;fer
  * @since Envoy Server Standalone v0.1-alpha
  */
 @Entity
 @Table(name = "users")
 @NamedQueries(
-	{ @NamedQuery(query = "SELECT u FROM User u WHERE u.name = :name", name = "getUserByName"),
-			@NamedQuery(query = "SELECT u.contacts FROM User u WHERE u = :user", name = "getContactsOfUser")// not tested
-	}
+	{ @NamedQuery(query = "SELECT u FROM User u WHERE u.name = :name", name = "getUserByName"), @NamedQuery(
+		query = "SELECT u.contacts FROM User u WHERE u = :user",
+		name = "getContactsOfUser"
+	), @NamedQuery(
+		query = "SELECT u FROM User u WHERE (lower(u.name) LIKE lower(:searchPhrase) AND u <> :context AND NOT :context in elements(u.contacts))",
+		name = "searchUsers"
+	) }
 )
 public class User {
 
@@ -37,7 +42,7 @@ public class User {
 	private Date						lastSeen;
 	private envoy.data.User.UserStatus	status;
 
-	@OneToMany(targetEntity = User.class, cascade = CascadeType.ALL, orphanRemoval = true)
+	@ManyToMany(targetEntity = User.class, cascade = CascadeType.ALL)
 	private List<User> contacts;
 
 	/**
diff --git a/src/main/java/envoy/server/database/PersistenceManager.java b/src/main/java/envoy/server/database/PersistenceManager.java
index 84587e6..8943f52 100644
--- a/src/main/java/envoy/server/database/PersistenceManager.java
+++ b/src/main/java/envoy/server/database/PersistenceManager.java
@@ -177,12 +177,44 @@ public class PersistenceManager {
 	}
 
 	/**
-	 * @param user the User whose contacts should be retrieved
-	 * @return the contacts of this User - currently everyone using Envoy
+	 * Searches for users matching a search phrase. Contacts of the attached user
+	 * and the attached user is ignored.
+	 *
+	 * @param searchPhrase the search phrase
+	 * @param userId       the ID of the user in whose context the search is
+	 *                     performed
+	 * @return a list of all users who matched the criteria
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public List<User> getContacts(User user) { return entityManager.createQuery("FROM User").getResultList(); }
-	// TODO current solution gets all users, not just contacts. Should be changed to
-	// entityManager.createNamedQuery("getContactsOfUser").setParameter("user",
-	// user).getResultList();
+	public List<User> searchUsers(String searchPhrase, long userId) {
+		return entityManager.createNamedQuery("searchUsers")
+			.setParameter("searchPhrase", searchPhrase + "%")
+			.setParameter("context", getUserById(userId))
+			.getResultList();
+	}
+
+	/**
+	 * Adds a user to the contact list of another user and vice versa.
+	 *
+	 * @param userId1 the ID of the first user
+	 * @param userId2 the ID of the second user
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public void addContact(long userId1, long userId2) {
+		User	u1	= getUserById(userId1);
+		User	u2	= getUserById(userId2);
+		u1.getContacts().add(u2);
+		u2.getContacts().add(u1);
+		updateUser(u1);
+		updateUser(u2);
+	}
+
+	/**
+	 * @param user the User whose contacts should be retrieved
+	 * @return the contacts of this User
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public List<User> getContacts(User user) {
+		return entityManager.createNamedQuery("getContactsOfUser").setParameter("user", user).getResultList();
+	}
 }
\ No newline at end of file
diff --git a/src/main/java/envoy/server/processors/ContactOperationProcessor.java b/src/main/java/envoy/server/processors/ContactOperationProcessor.java
new file mode 100644
index 0000000..48ec6d9
--- /dev/null
+++ b/src/main/java/envoy/server/processors/ContactOperationProcessor.java
@@ -0,0 +1,46 @@
+package envoy.server.processors;
+
+import java.io.IOException;
+import java.util.Arrays;
+
+import envoy.data.Contacts;
+import envoy.event.ContactOperationEvent;
+import envoy.server.ConnectionManager;
+import envoy.server.ObjectProcessor;
+import envoy.server.database.PersistenceManager;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>ContactOperationProcessor.java</strong><br>
+ * Created: <strong>08.02.2020</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+public class ContactOperationProcessor implements ObjectProcessor<ContactOperationEvent> {
+
+	private static final ConnectionManager connectionManager = ConnectionManager.getInstance();
+
+	@Override
+	public void process(ContactOperationEvent evt, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		switch (evt.getOperationType()) {
+			case ADD:
+				final long userId = ConnectionManager.getInstance().getUserIdBySocketId(socketId);
+				final long contactId = evt.get().getId();
+
+				System.out.printf("Adding user %s to the contact list of user %d.%n", evt.get(), userId);
+				PersistenceManager.getPersistenceManager().addContact(userId, contactId);
+
+				// Notify the contact if online
+				if (ConnectionManager.getInstance().isOnline(contactId)) writeProxy.write(connectionManager.getSocketId(contactId),
+						new Contacts(Arrays.asList(PersistenceManager.getPersistenceManager().getUserById(userId).toCommonUser())));
+				break;
+			default:
+				System.err.printf("Received %s with an unsupported operation.%n", evt);
+		}
+	}
+
+	@Override
+	public Class<ContactOperationEvent> getInputClass() { return ContactOperationEvent.class; }
+}
diff --git a/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java b/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java
new file mode 100644
index 0000000..e96c16e
--- /dev/null
+++ b/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java
@@ -0,0 +1,45 @@
+package envoy.server.processors;
+
+import java.io.IOException;
+import java.util.stream.Collectors;
+
+import envoy.data.Contacts;
+import envoy.event.ContactSearchRequest;
+import envoy.event.ContactSearchResult;
+import envoy.server.ConnectionManager;
+import envoy.server.ObjectProcessor;
+import envoy.server.data.User;
+import envoy.server.database.PersistenceManager;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>ContactsRequestEventProcessor.java</strong><br>
+ * Created: <strong>08.02.2020</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @author Maximilian K&auml;fer
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+public class ContactsRequestEventProcessor implements ObjectProcessor<ContactSearchRequest> {
+
+	/**
+	 * Writes a {@link Contacts} list to the client containing all {@link User}s
+	 * matching the search phrase contained inside the request. The client and their
+	 * contacts are excluded from the result.
+	 *
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	@Override
+	public void process(ContactSearchRequest request, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		writeProxy.write(socketId,
+				new ContactSearchResult(PersistenceManager.getPersistenceManager()
+					.searchUsers(request.get(), ConnectionManager.getInstance().getUserIdBySocketId(socketId))
+					.stream()
+					.map(User::toCommonUser)
+					.collect(Collectors.toList())));
+	}
+
+	@Override
+	public Class<ContactSearchRequest> getInputClass() { return ContactSearchRequest.class; }
+}
diff --git a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index 4a7f2c8..c7475e9 100644
--- a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
+++ b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -1,9 +1,7 @@
 package envoy.server.processors;
 
 import java.io.IOException;
-import java.util.Arrays;
-import java.util.Date;
-import java.util.List;
+import java.util.*;
 import java.util.stream.Collectors;
 
 import envoy.data.Contacts;
@@ -52,8 +50,7 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 		UserStatusChangeProcessor.updateUserStatus(user);
 
 		// Create contacts
-		Contacts contacts = new Contacts(user.getId(),
-				user.getContacts().stream().map(envoy.server.data.User::toCommonUser).collect(Collectors.toList()));
+		Contacts contacts = new Contacts(user.getContacts().stream().map(envoy.server.data.User::toCommonUser).collect(Collectors.toList()));
 		contacts.getContacts().add(user.toCommonUser());
 
 		// Complete handshake
@@ -81,8 +78,8 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 			user.setLastSeen(new Date());
 			user.setStatus(User.UserStatus.ONLINE);
 			user.setPasswordHash(credentials.getPasswordHash());
-			user.setContacts(PersistenceManager.getPersistenceManager().getContacts(user));
 			persistenceManager.addUser(user);
+			user.setContacts(new ArrayList<>());
 		} else {
 			user = persistenceManager.getUserByName(credentials.getName());
 			// TODO: Implement error when user does not exist