diff --git a/bin/get-server-block-attributes.php b/bin/get-server-block-attributes.php
new file mode 100755
index 00000000000000..0570ab9ba8add5
--- /dev/null
+++ b/bin/get-server-block-attributes.php
@@ -0,0 +1,38 @@
+#!/usr/bin/env php
+<?php
+/**
+ * Generates server-registered block attributes, writing to standard output.
+ *
+ * @package gutenberg-build
+ */
+
+$attributes = array();
+
+/**
+ * Register a block type. Substitute for core API in lieu of loading full
+ * WordPress context.
+ *
+ * @param string $name Block type name including namespace.
+ * @param array  $args {
+ *     Optional. Array of block type arguments. Any arguments may be defined, however the
+ *     ones described below are supported by default. Default empty array.
+ *
+ *     @type callable $render_callback Callback used to render blocks of this block type.
+ *     @type array    $attributes      Block attributes mapping, property name to schema.
+ * }
+ */
+function register_block_type( $name, $args = array() ) {
+	if ( ! isset( $args['attributes'] ) ) {
+		return;
+	}
+
+	global $attributes;
+	$attributes[ $name ] = $args['attributes'];
+}
+
+// Register server-side code for individual blocks.
+foreach ( glob( dirname( dirname( __FILE__ ) ) . '/blocks/library/*/index.php' ) as $block_logic ) {
+	require_once $block_logic;
+}
+
+echo json_encode( $attributes, JSON_PRETTY_PRINT );
diff --git a/blocks/api/registration.js b/blocks/api/registration.js
index 2bf153fcd023dd..afdaf742df82e8 100644
--- a/blocks/api/registration.js
+++ b/blocks/api/registration.js
@@ -3,7 +3,7 @@
 /**
  * External dependencies
  */
-import { isFunction, some } from 'lodash';
+import { get, isFunction, some } from 'lodash';
 
 /**
  * WordPress dependencies
@@ -92,8 +92,13 @@ export function registerBlockType( name, settings ) {
 		);
 		return;
 	}
-	const block = Object.assign( { name }, settings );
-	blocks[ name ] = block;
+
+	const block = blocks[ name ] = {
+		name,
+		attributes: get( window._wpBlocksAttributes, name ),
+		...settings,
+	};
+
 	return block;
 }
 
diff --git a/blocks/api/test/registration.js b/blocks/api/test/registration.js
index c177deb4fa7c13..46ca432c063de7 100644
--- a/blocks/api/test/registration.js
+++ b/blocks/api/test/registration.js
@@ -34,6 +34,7 @@ describe( 'blocks', () => {
 		} );
 		setUnknownTypeHandlerName( undefined );
 		setDefaultBlockName( undefined );
+		window._wpBlocksAttributes = {};
 		console.error = error;
 	} );
 
@@ -109,6 +110,23 @@ describe( 'blocks', () => {
 			expect( block ).toBeUndefined();
 		} );
 
+		it( 'should default to browser-initialized global attributes', () => {
+			const attributes = { ok: { type: 'boolean' } };
+			window._wpBlocksAttributes = {
+				'core/test-block-with-attributes': attributes,
+			};
+
+			const blockType = { settingName: 'settingValue', save: noop, category: 'common' };
+			registerBlockType( 'core/test-block-with-attributes', blockType );
+			expect( getBlockType( 'core/test-block-with-attributes' ) ).toEqual( {
+				name: 'core/test-block-with-attributes',
+				settingName: 'settingValue',
+				save: noop,
+				category: 'common',
+				attributes,
+			} );
+		} );
+
 		it( 'should store a copy of block type', () => {
 			const blockType = { settingName: 'settingValue', save: noop, category: 'common' };
 			registerBlockType( 'core/test-block-with-settings', blockType );
diff --git a/blocks/library/latest-posts/index.js b/blocks/library/latest-posts/index.js
index 6e4e865ea5b27c..7ccdc7a2ee2aaf 100644
--- a/blocks/library/latest-posts/index.js
+++ b/blocks/library/latest-posts/index.js
@@ -36,28 +36,6 @@ registerBlockType( 'core/latest-posts', {
 
 	keywords: [ __( 'recent posts' ) ],
 
-	attributes: {
-		postsToShow: {
-			type: 'number',
-			default: 5,
-		},
-		displayPostDate: {
-			type: 'boolean',
-			default: false,
-		},
-		layout: {
-			type: 'string',
-			default: 'list',
-		},
-		columns: {
-			type: 'number',
-			default: 3,
-		},
-		align: {
-			type: 'string',
-		},
-	},
-
 	getEditWrapperProps( attributes ) {
 		const { align } = attributes;
 		if ( 'left' === align || 'right' === align || 'wide' === align || 'full' === align ) {
diff --git a/blocks/library/latest-posts/index.php b/blocks/library/latest-posts/index.php
index 978f1374da40eb..9335cdebdae7d3 100644
--- a/blocks/library/latest-posts/index.php
+++ b/blocks/library/latest-posts/index.php
@@ -13,27 +13,8 @@
  * @return string Returns the post content with latest posts added.
  */
 function gutenberg_render_block_core_latest_posts( $attributes ) {
-	$posts_to_show = 5;
-
-	if ( array_key_exists( 'postsToShow', $attributes ) ) {
-
-		// Basic attribute validation.
-		if (
-			is_numeric( $attributes['postsToShow'] ) &&
-			$attributes['postsToShow'] > 0 &&
-			$attributes['postsToShow'] < 100
-		) {
-			$posts_to_show = intval( $attributes['postsToShow'] );
-		}
-	}
-
-	$align = 'center';
-	if ( isset( $attributes['align'] ) && in_array( $attributes['align'], array( 'left', 'right', 'wide', 'full' ), true ) ) {
-		$align = $attributes['align'];
-	}
-
 	$recent_posts = wp_get_recent_posts( array(
-		'numberposts' => $posts_to_show,
+		'numberposts' => $attributes['postsToShow'],
 		'post_status' => 'publish',
 	) );
 
@@ -63,7 +44,7 @@ function gutenberg_render_block_core_latest_posts( $attributes ) {
 		$list_items_markup .= "</li>\n";
 	}
 
-	$class = "wp-block-latest-posts align{$align}";
+	$class = "wp-block-latest-posts align{$attributes['align']}";
 	if ( isset( $attributes['layout'] ) && 'grid' === $attributes['layout'] ) {
 		$class .= ' is-grid';
 	}
@@ -82,5 +63,28 @@ function gutenberg_render_block_core_latest_posts( $attributes ) {
 }
 
 register_block_type( 'core/latest-posts', array(
+	'attributes' => array(
+		'postsToShow' => array(
+			'type' => 'number',
+			'default' => 5,
+		),
+		'displayPostDate' => array(
+			'type' => 'boolean',
+			'default' => false,
+		),
+		'layout' => array(
+			'type' => 'string',
+			'default' => 'list',
+		),
+		'columns' => array(
+			'type' => 'number',
+			'default' => 3,
+		),
+		'align' => array(
+			'type' => 'string',
+			'default' => 'center',
+		),
+	),
+
 	'render_callback' => 'gutenberg_render_block_core_latest_posts',
 ) );
diff --git a/blocks/test/fixtures/core__latest-posts.json b/blocks/test/fixtures/core__latest-posts.json
index c1e9e6f8d44334..8f17313f15f966 100644
--- a/blocks/test/fixtures/core__latest-posts.json
+++ b/blocks/test/fixtures/core__latest-posts.json
@@ -7,7 +7,8 @@
             "postsToShow": 5,
             "displayPostDate": false,
             "layout": "list",
-            "columns": 3
+            "columns": 3,
+            "align": "center"
         }
     }
 ]
diff --git a/blocks/test/fixtures/core__latest-posts__displayPostDate.json b/blocks/test/fixtures/core__latest-posts__displayPostDate.json
index 238718c80ea868..58ed17cb9dc059 100644
--- a/blocks/test/fixtures/core__latest-posts__displayPostDate.json
+++ b/blocks/test/fixtures/core__latest-posts__displayPostDate.json
@@ -7,7 +7,8 @@
             "postsToShow": 5,
             "displayPostDate": true,
             "layout": "list",
-            "columns": 3
+            "columns": 3,
+            "align": "center"
         }
     }
 ]
diff --git a/blocks/test/full-content.js b/blocks/test/full-content.js
index daf002e8c9ccc1..4601439d9b3608 100644
--- a/blocks/test/full-content.js
+++ b/blocks/test/full-content.js
@@ -89,6 +89,8 @@ function normalizeParsedBlocks( blocks ) {
 
 describe( 'full post content fixture', () => {
 	beforeAll( () => {
+		window._wpBlocksAttributes = require( './server-attributes.json' );
+
 		// Register all blocks.
 		require( 'blocks' );
 	} );
diff --git a/blocks/test/server-attributes.json b/blocks/test/server-attributes.json
new file mode 100644
index 00000000000000..ffbc5ddd6aad97
--- /dev/null
+++ b/blocks/test/server-attributes.json
@@ -0,0 +1,24 @@
+{
+    "core\/latest-posts": {
+        "postsToShow": {
+            "type": "number",
+            "default": 5
+        },
+        "displayPostDate": {
+            "type": "boolean",
+            "default": false
+        },
+        "layout": {
+            "type": "string",
+            "default": "list"
+        },
+        "columns": {
+            "type": "number",
+            "default": 3
+        },
+        "align": {
+            "type": "string",
+            "default": "center"
+        }
+    }
+}
\ No newline at end of file
diff --git a/lib/class-wp-block-type-registry.php b/lib/class-wp-block-type-registry.php
index a715f109cdda79..3c0c5221dba910 100644
--- a/lib/class-wp-block-type-registry.php
+++ b/lib/class-wp-block-type-registry.php
@@ -45,6 +45,7 @@ final class WP_Block_Type_Registry {
 	 *     ones described below are supported by default. Default empty array.
 	 *
 	 *     @type callable $render_callback Callback used to render blocks of this block type.
+	 *     @type array    $attributes      Block attributes mapping, property name to schema.
 	 * }
 	 * @return WP_Block_Type|false The registered block type on success, or false on failure.
 	 */
diff --git a/lib/class-wp-block-type.php b/lib/class-wp-block-type.php
index e66f1083e4e03b..930e711aed661a 100644
--- a/lib/class-wp-block-type.php
+++ b/lib/class-wp-block-type.php
@@ -32,6 +32,15 @@ class WP_Block_Type {
 	 */
 	public $render_callback;
 
+	/**
+	 * Block type attributes property schemas.
+	 *
+	 * @since 0.10.0
+	 * @access public
+	 * @var array
+	 */
+	public $attributes;
+
 	/**
 	 * Constructor.
 	 *
@@ -71,9 +80,45 @@ public function render( $attributes = array(), $content = null ) {
 			return $content;
 		}
 
+		$attributes = $this->prepare_attributes_for_render( $attributes );
+
 		return call_user_func( $this->render_callback, $attributes, $content );
 	}
 
+	/**
+	 * Validates attributes against the current block schema, populating
+	 * defaulted and missing values, and omitting unknown attributes.
+	 *
+	 * @param  array $attributes Original block attributes.
+	 * @return array             Prepared block attributes.
+	 */
+	public function prepare_attributes_for_render( $attributes ) {
+		if ( ! isset( $this->attributes ) ) {
+			return $attributes;
+		}
+
+		$prepared_attributes = array();
+
+		foreach ( $this->attributes as $attribute_name => $schema ) {
+			$value = null;
+
+			if ( isset( $attributes[ $attribute_name ] ) ) {
+				$is_valid = rest_validate_value_from_schema( $attributes[ $attribute_name ], $schema );
+				if ( ! is_wp_error( $is_valid ) ) {
+					$value = $attributes[ $attribute_name ];
+				}
+			}
+
+			if ( is_null( $value ) && isset( $schema['default'] ) ) {
+				$value = $schema['default'];
+			}
+
+			$prepared_attributes[ $attribute_name ] = $value;
+		}
+
+		return $prepared_attributes;
+	}
+
 	/**
 	 * Sets block type properties.
 	 *
diff --git a/lib/client-assets.php b/lib/client-assets.php
index 77ce1758361ad2..71684f7c628a77 100644
--- a/lib/client-assets.php
+++ b/lib/client-assets.php
@@ -769,6 +769,16 @@ function gutenberg_editor_scripts_and_styles( $hook ) {
 		'before'
 	);
 
+	// Preload server-registered block schemas.
+	$block_registry = WP_Block_Type_Registry::get_instance();
+	$schemas = array();
+	foreach ( $block_registry->get_all_registered() as $block_name => $block_type ) {
+		if ( isset( $block_type->attributes ) ) {
+			$schemas[ $block_name ] = $block_type->attributes;
+		}
+	}
+	wp_localize_script( 'wp-blocks', '_wpBlocksAttributes', $schemas );
+
 	// Initialize the editor.
 	$gutenberg_theme_support = get_theme_support( 'gutenberg' );
 	$color_palette = gutenberg_color_palette();
diff --git a/package.json b/package.json
index 86189f7d33403a..e8a764e588b04f 100644
--- a/package.json
+++ b/package.json
@@ -135,7 +135,8 @@
     "test": "npm run lint && npm run test-unit",
     "ci": "concurrently \"npm run lint && npm run build\" \"npm run test-unit:coverage-ci\"",
     "fixtures:clean": "rimraf \"blocks/test/fixtures/*.+(json|serialized.html)\"",
-    "fixtures:generate": "cross-env GENERATE_MISSING_FIXTURES=y npm run test-unit",
+    "fixtures:server-attributes": "./bin/get-server-block-attributes.php > blocks/test/server-attributes.json",
+    "fixtures:generate": "npm run fixtures:server-attributes && cross-env GENERATE_MISSING_FIXTURES=y npm run test-unit",
     "fixtures:regenerate": "npm run fixtures:clean && npm run fixtures:generate",
     "package-plugin": "./bin/build-plugin-zip.sh",
     "docs-start": "./docutron/bin/cli.js start",
diff --git a/phpunit/class-block-type-test.php b/phpunit/class-block-type-test.php
index 213f182c572652..dfa776cca10379 100644
--- a/phpunit/class-block-type-test.php
+++ b/phpunit/class-block-type-test.php
@@ -63,6 +63,44 @@ function test_render_without_callback() {
 		$this->assertSame( $content, $output );
 	}
 
+	function test_prepare_attributes() {
+		$attributes = array(
+			'correct'            => 'include',
+			'wrongType'          => 5,
+			'wrongTypeDefaulted' => 5,
+			/* missingDefaulted */
+			'undefined'          => 'omit',
+		);
+
+		$block_type = new WP_Block_Type( 'core/dummy', array(
+			'attributes' => array(
+				'correct' => array(
+					'type' => 'string',
+				),
+				'wrongType' => array(
+					'type' => 'string',
+				),
+				'wrongTypeDefaulted' => array(
+					'type'    => 'string',
+					'default' => 'defaulted',
+				),
+				'missingDefaulted' => array(
+					'type'    => 'string',
+					'default' => 'define',
+				),
+			),
+		) );
+
+		$prepared_attributes = $block_type->prepare_attributes_for_render( $attributes );
+
+		$this->assertEquals( array(
+			'correct'            => 'include',
+			'wrongType'          => null,
+			'wrongTypeDefaulted' => 'defaulted',
+			'missingDefaulted'   => 'define',
+		), $prepared_attributes );
+	}
+
 	function render_dummy_block( $attributes ) {
 		return json_encode( $attributes );
 	}