diff --git a/src/pocketmine/Player.php b/src/pocketmine/Player.php
index 407c469fb..be4542a9d 100644
--- a/src/pocketmine/Player.php
+++ b/src/pocketmine/Player.php
@@ -66,6 +66,8 @@ use pocketmine\event\player\PlayerToggleSneakEvent;
 use pocketmine\event\player\PlayerToggleSprintEvent;
 use pocketmine\event\player\PlayerTransferEvent;
 use pocketmine\event\server\DataPacketSendEvent;
+use pocketmine\form\Form;
+use pocketmine\form\FormValidationException;
 use pocketmine\inventory\CraftingGrid;
 use pocketmine\inventory\Inventory;
 use pocketmine\inventory\PlayerCursorInventory;
@@ -116,6 +118,7 @@ use pocketmine\network\mcpe\protocol\LevelSoundEventPacket;
 use pocketmine\network\mcpe\protocol\LoginPacket;
 use pocketmine\network\mcpe\protocol\MobEffectPacket;
 use pocketmine\network\mcpe\protocol\MobEquipmentPacket;
+use pocketmine\network\mcpe\protocol\ModalFormRequestPacket;
 use pocketmine\network\mcpe\protocol\MovePlayerPacket;
 use pocketmine\network\mcpe\protocol\PlayerActionPacket;
 use pocketmine\network\mcpe\protocol\PlayStatusPacket;
@@ -323,6 +326,11 @@ class Player extends Human implements CommandSender, ChunkLoader, IPlayer{
 	/** @var int[] ID => ticks map */
 	protected $usedItemsCooldown = [];
 
+	/** @var int */
+	protected $formIdCounter = 0;
+	/** @var Form[] */
+	protected $forms = [];
+
 	/**
 	 * @return TranslationContainer|string
 	 */
@@ -3353,6 +3361,48 @@ class Player extends Human implements CommandSender, ChunkLoader, IPlayer{
 		$this->dataPacket($pk);
 	}
 
+	/**
+	 * Sends a Form to the player, or queue to send it if a form is already open.
+	 *
+	 * @param Form $form
+	 */
+	public function sendForm(Form $form) : void{
+		$id = $this->formIdCounter++;
+		$pk = new ModalFormRequestPacket();
+		$pk->formId = $id;
+		$pk->formData = json_encode($form);
+		if($this->dataPacket($pk)){
+			$this->forms[$id] = $form;
+		}
+	}
+
+	/**
+	 * @param int   $formId
+	 * @param mixed $responseData
+	 *
+	 * @return bool
+	 */
+	public function onFormSubmit(int $formId, $responseData) : bool{
+		if(!isset($this->forms[$formId])){
+			$this->server->getLogger()->debug("Got unexpected response for form $formId");
+			return false;
+		}
+
+		try{
+			$next = $this->forms[$formId]->handleResponse($this, $responseData);
+			if($next !== null){
+				$this->sendForm($next);
+			}
+		}catch(FormValidationException $e){
+			$this->server->getLogger()->critical("Failed to validate form " . get_class($this->forms[$formId]) . ": " . $e->getMessage());
+			$this->server->getLogger()->logException($e);
+		}finally{
+			unset($this->forms[$formId]);
+		}
+
+		return true;
+	}
+
 	/**
 	 * Note for plugin developers: use kick() with the isAdmin
 	 * flag set to kick without the "Kicked by admin" part instead of this method.
diff --git a/src/pocketmine/form/Form.php b/src/pocketmine/form/Form.php
new file mode 100644
index 000000000..f822b1ceb
--- /dev/null
+++ b/src/pocketmine/form/Form.php
@@ -0,0 +1,44 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\form;
+
+use pocketmine\Player;
+
+/**
+ * Form implementations must implement this interface to be able to utilize the Player form-sending mechanism.
+ * There is no restriction on custom implementations other than that they must implement this.
+ */
+interface Form extends \JsonSerializable{
+
+	/**
+	 * Handles a form response from a player.
+	 *
+	 * @param Player $player
+	 * @param mixed  $data
+	 *
+	 * @return Form|null a form which will be opened immediately (before queued forms) as a response to this form, or null if not applicable.
+	 * @throws FormValidationException
+	 */
+	public function handleResponse(Player $player, $data) : ?Form;
+}
diff --git a/src/pocketmine/form/FormValidationException.php b/src/pocketmine/form/FormValidationException.php
new file mode 100644
index 000000000..df63c60c3
--- /dev/null
+++ b/src/pocketmine/form/FormValidationException.php
@@ -0,0 +1,28 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\form;
+
+class FormValidationException extends \RuntimeException{
+
+}
diff --git a/src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter.php b/src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter.php
index 385a64540..b8801815f 100644
--- a/src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter.php
+++ b/src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter.php
@@ -239,7 +239,7 @@ class PlayerNetworkSessionAdapter extends NetworkSession{
 	}
 
 	public function handleModalFormResponse(ModalFormResponsePacket $packet) : bool{
-		return false; //TODO: GUI stuff
+		return $this->player->onFormSubmit($packet->formId, json_decode($packet->formData, true));
 	}
 
 	public function handleServerSettingsRequest(ServerSettingsRequestPacket $packet) : bool{