diff --git a/bin/webpack.metaboxes.js b/bin/webpack.metaboxes.js
index f0ad20604..ca1834021 100644
--- a/bin/webpack.metaboxes.js
+++ b/bin/webpack.metaboxes.js
@@ -15,6 +15,10 @@ const config = {
 	entry: {
 		metaboxes: './packages/metaboxes/index.js'
 	},
+	output: {
+		library: [ 'cf', '[name]' ],
+		libraryTarget: 'this'
+	},
 	externals: {
 		'react': [ 'cf', 'vendor', 'react' ],
 		'react-dom': [ 'cf', 'vendor', 'react-dom' ],
diff --git a/core/REST_API/Router.php b/core/REST_API/Router.php
index 187aaae85..cf23f6039 100644
--- a/core/REST_API/Router.php
+++ b/core/REST_API/Router.php
@@ -287,25 +287,37 @@ public function get_comment_meta( $data ) {
 	/**
 	 * Get Carbon Fields association options data.
 	 *
+	 * @access public
+	 *
 	 * @return array
 	 */
 	public function get_association_data() {
 		$container_id = $_GET['container_id'];
 		$field_id     = $_GET['field_id'];
-		$options      = isset( $_GET['options'] ) ? $_GET['options'] : array();
+		$options      = isset( $_GET['options'] ) ? explode( ';', $_GET['options'] ) : array();
 		$return_value = array();
 
 		$field = Helper::get_field( null, $container_id, $field_id );
 
-		foreach ( $options as $entry ) {
+		$options = array_map( function ( $option ) {
+			$option = explode( ':', $option );
+
+			return [
+				'id'      => $option[0],
+				'type'    => $option[1],
+				'subtype' => $option[2],
+			];
+		}, $options );
+
+		foreach ( $options as $option ) {
 			$item = array(
-				'type'       => $entry['type'],
-				'subtype'    => $entry['subtype'],
-				'thumbnail'  => $field->get_thumbnail_by_type( $entry['id'], $entry['type'], $entry['subtype'] ),
-				'id'         => intval( $entry['id'] ),
-				'title'      => $field->get_title_by_type( $entry['id'], $entry['type'], $entry['subtype'] ),
-				'label'      => $field->get_item_label( $entry['id'], $entry['type'], $entry['subtype'] ),
-				'is_trashed' => ( $entry['type'] == 'post' && get_post_status( $entry['id'] ) === 'trash' ),
+				'type'       => $option['type'],
+				'subtype'    => $option['subtype'],
+				'thumbnail'  => $field->get_thumbnail_by_type( $option['id'], $option['type'], $option['subtype'] ),
+				'id'         => intval( $option['id'] ),
+				'title'      => $field->get_title_by_type( $option['id'], $option['type'], $option['subtype'] ),
+				'label'      => $field->get_item_label( $option['id'], $option['type'], $option['subtype'] ),
+				'is_trashed' => ( $option['type'] == 'post' && get_post_status( $option['id'] ) === 'trash' ),
 			);
 
 			$return_value[] = $item;
diff --git a/packages/core/fields/association/index.js b/packages/core/fields/association/index.js
index c15fd288a..fabafbc78 100644
--- a/packages/core/fields/association/index.js
+++ b/packages/core/fields/association/index.js
@@ -18,7 +18,6 @@ import {
 	without,
 	isMatch,
 	isEmpty
-
 } from 'lodash';
 import {
 	combine,
@@ -44,6 +43,13 @@ class AssociationField extends Component {
 	 */
 	selectedList = createRef();
 
+	/**
+	 * Keeps reference to the DOM bnode that contains the options.
+	 *
+	 * @type {Object}
+	 */
+	sourceList = createRef();
+
 	/**
 	 * Lifecycle hook.
 	 *
@@ -65,6 +71,47 @@ class AssociationField extends Component {
 		if ( value ) {
 			fetchSelectedOptions();
 		}
+
+		this.sourceList.current.addEventListener( 'scroll', this.handleSourceListScroll );
+	}
+
+	/**
+	 * Lifecycle hook.
+	 *
+	 * @return {void}
+	 */
+	componentWillUnmount() {
+		this.sourceList.current.removeEventListener( 'scroll', this.handleSourceListScroll );
+	}
+
+	/**
+	 * Handles the scroll event of the source list.
+	 *
+	 * @return {void}
+	 */
+	handleSourceListScroll = () => {
+		const {
+			fetchOptions,
+			setState,
+			options,
+			page,
+			queryTerm
+		} = this.props;
+
+		const sourceList = this.sourceList.current;
+
+		if ( sourceList.offsetHeight + sourceList.scrollTop === sourceList.scrollHeight ) {
+			setState( {
+				page: page + 1
+			} );
+
+			fetchOptions( {
+				type: 'append',
+				options: options,
+				queryTerm,
+				page: page + 1
+			} );
+		}
 	}
 
 	/**
@@ -79,8 +126,16 @@ class AssociationField extends Component {
 			setState
 		} = this.props;
 
-		setState( { queryTerm } );
-		fetchOptions( { queryTerm } );
+		setState( {
+			page: 1,
+			queryTerm
+		} );
+
+		fetchOptions( {
+			type: 'replace',
+			page: 1,
+			queryTerm
+		} );
 	}
 
 	/**
@@ -172,7 +227,8 @@ class AssociationField extends Component {
 			field,
 			totalOptionsCount,
 			selectedOptions,
-			queryTerm
+			queryTerm,
+			isLoading
 		} = this.props;
 
 		let { options } = this.props;
@@ -199,6 +255,12 @@ class AssociationField extends Component {
 						onChange={ this.handleSearchChange }
 					/>
 
+					{
+						isLoading
+							? <span className="cf-association__spinner spinner is-active"></span>
+							: ''
+					}
+
 					<span className="cf-association__counter">
 						{ sprintf(
 							__( 'Showing %1$d of %2$d results', 'carbon-fields-ui' ),
@@ -209,7 +271,7 @@ class AssociationField extends Component {
 				</div>
 
 				<div className="cf-association__cols">
-					<div className="cf-association__col">
+					<div className="cf-association__col" ref={ this.sourceList }>
 						{
 							options.map( ( option, index ) => {
 								return (
@@ -220,7 +282,9 @@ class AssociationField extends Component {
 
 										<div className="cf-association__option-content">
 											<span className="cf-association__option-title">
-												{ option.title }
+												<span className="cf-association__option-title-inner">
+													{ option.title }
+												</span>
 											</span>
 
 											<span className="cf-association__option-type">
@@ -368,10 +432,15 @@ function handler( props ) {
 
 		switch ( type ) {
 			case 'FETCH_OPTIONS':
+				setState( {
+					isLoading: true
+				} );
+
 				// eslint-disable-next-line
 				const request = window.jQuery.get( window.ajaxurl, {
 					action: 'carbon_fields_fetch_association_options',
 					term: payload.queryTerm,
+					page: payload.page || 1,
 					container_id: props.containerId,
 					field_name: hierarchyResolver()
 				}, null, 'json' );
@@ -382,7 +451,7 @@ function handler( props ) {
 				request.done( ( response ) => {
 					if ( response && response.success ) {
 						setState( {
-							options: response.data.options,
+							options: payload.type === 'replace' ? response.data.options : [ ...payload.options, ...response.data.options ],
 							totalOptionsCount: response.data.total_options
 						} );
 					} else {
@@ -391,6 +460,11 @@ function handler( props ) {
 				} );
 
 				request.fail( errorHandler );
+				request.always( () => {
+					setState( {
+						isLoading: false
+					} );
+				} );
 				break;
 
 			case 'FETCH_SELECTED_OPTIONS':
@@ -399,7 +473,7 @@ function handler( props ) {
 					'get',
 					{
 						container_id: props.containerId,
-						options: props.value,
+						options: props.value.map( ( option ) => `${ option.id }:${ option.type }:${ option.subtype }` ).join( ';' ),
 						field_id: hierarchyResolver()
 					}
 				)
@@ -418,7 +492,9 @@ const applyWithState = withState( {
 	options: [],
 	selectedOptions: [],
 	totalOptionsCount: 0,
-	queryTerm: ''
+	queryTerm: '',
+	page: 1,
+	isLoading: false
 } );
 
 const applyWithEffects = withEffects( aperture, { handler } );
diff --git a/packages/core/fields/association/style.scss b/packages/core/fields/association/style.scss
index df0d1af27..889d06c16 100644
--- a/packages/core/fields/association/style.scss
+++ b/packages/core/fields/association/style.scss
@@ -5,17 +5,49 @@
 .cf-association__bar {
 	position: relative;
 	z-index: 1;
+	display: flex;
+	justify-content: space-between;
+	align-items: center;
+	flex-direction: row;
+	border-color: $wp-color-gray-light-500;
+	border-style: solid;
+	border-width: 1px 1px 0;
+	box-shadow: inset 0 1px 2px rgba( 0, 0, 0, 0.07 );
+
+	.cf-search-input {
+		flex: 1 1 auto;
+	}
+
+	.cf-search-input__inner {
+		border: 0;
+		box-shadow: none;
+
+		&:focus {
+			border-color: none;
+			box-shadow: none;
+			outline: none;
+		}
+	}
+
+	&:focus-within {
+		border-color: #5b9dd9;
+		box-shadow: 0 0 2px rgba( 30, 140, 190, 0.8 );
+		outline: 2px solid transparent;
+	}
 }
 
 .cf-association__counter {
-	position: absolute;
-	top: 50%;
-	right: 8px;
 	font-size: 12px;
-	line-height: 1;
 	color: $wp-color-dark-gray;
-	transform: translateY(-50%);
 	pointer-events: none;
+	margin-right: 5px;
+	margin-left: 5px;
+}
+
+.cf-association__spinner {
+	float: none;
+	margin: 0;
+	margin-left: 5px;
 }
 
 .cf-association__cols {
@@ -23,7 +55,7 @@
 	position: relative;
 	z-index: 0;
 	display: flex;
-	border-width: 0 1px 1px;
+	border-width: 1px;
 	border-style: solid;
 	border-color: $wp-color-gray-light-500;
 
@@ -83,12 +115,8 @@
 }
 
 .cf-association__option-title {
-	overflow: hidden;
-	font-size: $wp-font-size;
-	line-height: $wp-line-height;
-	color: $wp-color-base-gray;
-	white-space: nowrap;
-	text-overflow: ellipsis;
+	flex: 1;
+	position: relative;
 	margin-right: $size-base;
 
 	.cf-association__option--selected & {
@@ -96,6 +124,20 @@
 	}
 }
 
+.cf-association__option-title-inner {
+	position: absolute;
+	top: 0;
+	left: 0;
+	width: 100%;
+	font-size: $wp-font-size;
+	line-height: $wp-line-height;
+	color: $wp-color-base-gray;
+	overflow: hidden;
+	white-space: nowrap;
+	text-overflow: ellipsis;
+	transform: translateY(-50%);
+}
+
 .cf-association__option-type {
 	font-size: 9px;
 	line-height: 1;
diff --git a/packages/metaboxes/containers/index.js b/packages/metaboxes/containers/index.js
index d1d13a635..e86e3d171 100644
--- a/packages/metaboxes/containers/index.js
+++ b/packages/metaboxes/containers/index.js
@@ -45,7 +45,10 @@ export function renderContainer( container, context ) {
 	if ( node ) {
 		render(
 			<Component id={ container.id } />,
-			node
+			node,
+			() => {
+				node.dataset.mounted = true;
+			}
 		);
 	} else {
 		// eslint-disable-next-line no-console
diff --git a/packages/metaboxes/index.js b/packages/metaboxes/index.js
index 4f4fe1832..4d85d20c1 100644
--- a/packages/metaboxes/index.js
+++ b/packages/metaboxes/index.js
@@ -13,6 +13,11 @@ import initializeMonitors from './monitors';
 import initializeContainers from './containers';
 import isGutenberg from './utils/is-gutenberg';
 
+/**
+ * Public API.
+ */
+export { registerContainerType, getContainerType } from './containers/registry';
+
 /**
  * Sets the locale data for the package type
  */
diff --git a/packages/metaboxes/monitors/conditional-display/aperture/post-template.js b/packages/metaboxes/monitors/conditional-display/aperture/post-template.js
index a7bf4ea71..c5f0f9678 100644
--- a/packages/metaboxes/monitors/conditional-display/aperture/post-template.js
+++ b/packages/metaboxes/monitors/conditional-display/aperture/post-template.js
@@ -35,8 +35,15 @@ const INITIAL_STATE = {
  * @return {Object}
  */
 function getPostTemplateFromSelect( node ) {
+	let { value } = node;
+
+	// In Gutenberg for the "Default" template is used an empty string.
+	if ( value === 'default' ) {
+		value = '';
+	}
+
 	return {
-		post_template: node.value
+		post_template: value
 	};
 }
 
diff --git a/packages/metaboxes/monitors/conditional-display/conditions/post-template.js b/packages/metaboxes/monitors/conditional-display/conditions/post-template.js
new file mode 100644
index 000000000..d6e4c9fc1
--- /dev/null
+++ b/packages/metaboxes/monitors/conditional-display/conditions/post-template.js
@@ -0,0 +1,22 @@
+/**
+ * Internal dependencies.
+ */
+import base from './base';
+
+export default {
+	...base,
+
+	/**
+	 * @inheritdoc
+	 */
+	isFulfiled( definition, values ) {
+		definition = { ...definition };
+
+		// In Gutenberg for the "Default" template is used an empty string.
+		if ( definition.value === 'default' ) {
+			definition.value = '';
+		}
+
+		return base.isFulfiled( definition, values );
+	}
+};
diff --git a/packages/metaboxes/monitors/conditional-display/handler/index.js b/packages/metaboxes/monitors/conditional-display/handler/index.js
index 22b324f47..f6bba8aaf 100644
--- a/packages/metaboxes/monitors/conditional-display/handler/index.js
+++ b/packages/metaboxes/monitors/conditional-display/handler/index.js
@@ -1,7 +1,6 @@
 /**
  * External dependencies.
  */
-import { unmountComponentAtNode } from '@wordpress/element';
 import { __, sprintf } from '@wordpress/i18n';
 import { get, map } from 'lodash';
 
@@ -12,6 +11,7 @@ import { renderContainer } from '../../../containers';
 import base from '../conditions/base';
 import boolean from '../conditions/boolean';
 import postTerm from '../conditions/post-term';
+import postTemplate from '../conditions/post-template';
 import postAncestorId from '../conditions/post-ancestor-id';
 import termParentId from '../conditions/term-parent-id';
 import termAncestorId from '../conditions/term-ancestor-id';
@@ -28,7 +28,7 @@ const conditions = {
 	post_parent_id: base,
 	post_level: base,
 	post_format: base,
-	post_template: base,
+	post_template: postTemplate,
 	term_level: base,
 	term_parent: termParentId,
 	term_ancestor: termAncestorId,
@@ -96,22 +96,25 @@ export default function handler( { containers, context } ) {
 		results.forEach( ( [ id, result ] ) => {
 			const postboxNode = document.getElementById( id );
 			const containerNode = document.querySelector( `.container-${ id }` );
+			const isMounted = !! containerNode.dataset.mounted;
 
 			if ( postboxNode ) {
 				postboxNode.hidden = ! result;
 			}
 
 			if ( containerNode ) {
-				if ( result && ! containerNode.dataset.mounted ) {
-					containerNode.dataset.mounted = true;
-
+				if ( result && ! isMounted ) {
 					renderContainer( containers[ id ], context );
 				}
 
-				if ( ! result && containerNode.dataset.mounted ) {
+				if ( ! result && isMounted ) {
 					delete containerNode.dataset.mounted;
 
-					unmountComponentAtNode( containerNode );
+					// Rely on React's internals instead of `unmountComponentAtNode`
+					// due to https://github.com/facebook/react/issues/13690.
+					// TODO: Conditionally render the fields in the container, this way
+					// we can move away from mount/unmount cycles.
+					containerNode._reactRootContainer.unmount();
 				}
 			}
 		} );
diff --git a/packages/metaboxes/utils/is-gutenberg.js b/packages/metaboxes/utils/is-gutenberg.js
index 63eeeb46b..2e0de431b 100644
--- a/packages/metaboxes/utils/is-gutenberg.js
+++ b/packages/metaboxes/utils/is-gutenberg.js
@@ -6,11 +6,8 @@ import { isUndefined } from 'lodash';
 /**
  * Returns true if Gutenberg is presented.
  *
- * For some reason the Gutenberg package uses `_wpLoadGutenbergEditor`
- * while WordPress@5 uses `_wpLoadBlockEditor`.
- *
  * @return {boolean}
  */
 export default function isGutenberg() {
-	return ! isUndefined( window._wpLoadGutenbergEditor ) || ! isUndefined( window._wpLoadBlockEditor );
+	return ! isUndefined( window._wpLoadBlockEditor );
 }