diff --git a/core/utils/deprecation.js b/core/utils/deprecation.ts
similarity index 61%
rename from core/utils/deprecation.js
rename to core/utils/deprecation.ts
index 907322ae5f6..bd5731d4712 100644
--- a/core/utils/deprecation.js
+++ b/core/utils/deprecation.ts
@@ -15,27 +15,29 @@
  * This method is not specific to Blockly.
  * @namespace Blockly.utils.deprecation
  */
-goog.module('Blockly.utils.deprecation');
+import * as goog from '../../closure/goog/goog.js';
+
+goog.declareModuleId('Blockly.utils.deprecation');
 
 
 /**
  * Warn developers that a function or property is deprecated.
- * @param {string} name The name of the function or property.
- * @param {string} deprecationDate The date of deprecation.
+ * @param name The name of the function or property.
+ * @param deprecationDate The date of deprecation.
  *     Prefer 'month yyyy' or 'quarter yyyy' format.
- * @param {string} deletionDate The date of deletion, in the same format as the
+ * @param deletionDate The date of deletion, in the same format as the
  *     deprecation date.
- * @param {string=} opt_use The name of a function or property to use instead,
- *     if any.
+ * @param opt_use The name of a function or property to use instead, if any.
  * @alias Blockly.utils.deprecation.warn
- * @package
+ * @internal
  */
-const warn = function(name, deprecationDate, deletionDate, opt_use) {
+export function warn(
+    name: string, deprecationDate: string, deletionDate: string,
+    opt_use?: string) {
   let msg = name + ' was deprecated on ' + deprecationDate +
       ' and will be deleted on ' + deletionDate + '.';
   if (opt_use) {
     msg += '\nUse ' + opt_use + ' instead.';
   }
   console.warn(msg);
-};
-exports.warn = warn;
+}
diff --git a/scripts/gulpfiles/build_tasks.js b/scripts/gulpfiles/build_tasks.js
index ce13aec18c1..3e709f940cf 100644
--- a/scripts/gulpfiles/build_tasks.js
+++ b/scripts/gulpfiles/build_tasks.js
@@ -174,7 +174,7 @@ var JSCOMP_ERROR = [
   // 'accessControls',  // Deprecated; means same as visibility.
   'checkPrototypalTypes',
   'checkRegExp',
-  'checkTypes',
+  // 'checkTypes',  // Disabled; see note in JSCOMP_OFF.
   'checkVars',
   'conformanceViolations',
   'const',
@@ -198,7 +198,7 @@ var JSCOMP_ERROR = [
   // 'missingSourcesWarnings',  // Group of several other options.
   'moduleLoad',
   'msgDescriptions',
-  'nonStandardJsDocs',
+  // 'nonStandardJsDocs',  // Disabled; see note in JSCOMP_OFF.
   // 'partialAlias',  // Don't want this to be an error yet; only warning.
   // 'polymer',  // Not applicable.
   // 'reportUnknownTypes',  // VERY verbose.
@@ -222,15 +222,36 @@ var JSCOMP_ERROR = [
 /**
  * Closure compiler diagnostic groups we want to be treated as warnings.
  * These are effected when the --debug or --strict flags are passed.
+ *
+ * For most (all?) diagnostic groups this is the default level, so
+ * it's generally sufficient to remove them from JSCOMP_ERROR.
  */
 var JSCOMP_WARNING = [
 ];
 
 /**
- * Closure compiler diagnostic groups we want to be ignored.
- * These suppressions are always effected by default.
+ * Closure compiler diagnostic groups we want to be ignored.  These
+ * suppressions are always effected by default.
+ *
+ * Make sure that anything added here is commented out of JSCOMP_ERROR
+ * above, as that takes precedence.)
  */
 var JSCOMP_OFF = [
+  /* The removal of Closure type system types from our JSDoc
+   * annotations means that the closure compiler now generates certain
+   * diagnostics because it no longer has enough information to be
+   * sure that the input code is correct.  The following diagnostic
+   * groups are turned off to suppress such errors.
+   *
+   * When adding additional items to this list it may be helpful to
+   * search the compiler source code
+   * (https://github.com/google/closure-compiler/) for the JSC_*
+   * disagnostic name (omitting the JSC_ prefix) to find the corresponding
+   * DiagnosticGroup.
+   */
+  'checkTypes',
+  'nonStandardJsDocs',  // Due to @internal
+
   /* In order to transition to ES modules, modules will need to import
    * one another by relative paths. This means that the previous
    * practice of moving all source files into the same directory for
@@ -269,12 +290,8 @@ function buildJavaScript(done) {
  * suite.
  */
 function buildDeps(done) {
-  const closurePath = argv.closureLibrary ?
-      'node_modules/google-closure-library/closure/goog' :
-      'closure/goog';
-
   const roots = [
-    closurePath,
+    path.join(TSC_OUTPUT_DIR, 'closure', 'goog', 'base.js'),
     TSC_OUTPUT_DIR,
     'blocks',
     'generators',
@@ -430,15 +447,15 @@ return ${exportsExpression};
  * @return {{chunk: !Array<string>, js: !Array<string>}} The chunking
  *     information, in the same form as emitted by
  *     closure-calculate-chunks.
- *
- * TODO(cpcallen): maybeAddClosureLibrary?  Or maybe remove base.js?
  */
 function getChunkOptions() {
   if (argv.compileTs) {
     chunks[0].entry = path.join(TSC_OUTPUT_DIR, chunks[0].entry);
   }
+  const basePath =
+      path.join(TSC_OUTPUT_DIR, 'closure', 'goog', 'base_minimal.js');
   const cccArgs = [
-    '--closure-library-base-js-path ./closure/goog/base_minimal.js',
+    `--closure-library-base-js-path ./${basePath}`,
     `--deps-file './${DEPS_FILE}'`,
     ...(chunks.map(chunk => `--entrypoint '${chunk.entry}'`)),
   ];
@@ -545,7 +562,11 @@ function compile(options) {
     language_out: 'ECMASCRIPT5_STRICT',
     jscomp_off: [...JSCOMP_OFF],
     rewrite_polyfills: true,
-    hide_warnings_for: 'node_modules',
+    // N.B.: goog.js refers to lots of properties on goog that are not
+    // declared by base_minimal.js, while if you compile against
+    // base.js instead you will discover that it uses @deprecated
+    // inherits, forwardDeclare etc.
+    hide_warnings_for: ['node_modules', 'build/src/closure/goog/goog.js'],
     define: ['COMPILED=true'],
   };
   if (argv.debug || argv.strict) {
@@ -597,11 +618,10 @@ function buildCompiled() {
  * closure compiler's ADVANCED_COMPILATION mode.
  */
 function buildAdvancedCompilationTest() {
-  const coreSrcs = argv.compileTs ?
-      TSC_OUTPUT_DIR + '/core/**/*.js' : 'core/**/*.js';
   const srcs = [
-    'closure/goog/base_minimal.js',
-    coreSrcs,
+    TSC_OUTPUT_DIR + '/closure/goog/base_minimal.js',
+    TSC_OUTPUT_DIR + '/closure/goog/goog.js',
+    TSC_OUTPUT_DIR + '/core/**/*.js',
     'blocks/**/*.js',
     'generators/**/*.js',
     'tests/compile/main.js',
@@ -668,7 +688,10 @@ function cleanBuildDir(done) {
  * Runs clang format on all files in the core directory.
  */
 function format() {
-  return gulp.src(['core/**/*.js', 'blocks/**/*.js'], {base: '.'})
+  return gulp.src([
+    'core/**/*.js', 'core/**/*.ts',
+    'blocks/**/*.js', 'blocks/**/*.ts'
+  ], {base: '.'})
       .pipe(clangFormatter.format('file', clangFormat))
       .pipe(gulp.dest('.'));
 };
diff --git a/scripts/gulpfiles/chunks.json b/scripts/gulpfiles/chunks.json
index 0ad47025dbe..d35ed7089ae 100644
--- a/scripts/gulpfiles/chunks.json
+++ b/scripts/gulpfiles/chunks.json
@@ -1,6 +1,6 @@
 {
   "chunk": [
-    "blockly:259",
+    "blockly:260",
     "blocks:10:blockly",
     "all:11:blockly",
     "all1:11:blockly",
@@ -250,6 +250,7 @@
     "./build/src/core/utils/parsing.js",
     "./build/src/core/extensions.js",
     "./build/src/core/block.js",
+    "./build/src/closure/goog/goog.js",
     "./build/src/core/utils/deprecation.js",
     "./build/src/core/utils/string.js",
     "./build/src/core/dialog.js",
@@ -266,7 +267,7 @@
     "./build/src/core/connection.js",
     "./build/src/core/common.js",
     "./build/src/core/blocks.js",
-    "./closure/goog/base_minimal.js",
+    "./build/src/closure/goog/base_minimal.js",
     "./build/src/core/blockly.js",
     "./blocks/variables_dynamic.js",
     "./blocks/variables.js",
diff --git a/tests/bootstrap.js b/tests/bootstrap.js
index 45f64bb193a..15c207c631b 100644
--- a/tests/bootstrap.js
+++ b/tests/bootstrap.js
@@ -134,7 +134,8 @@
     // libary we use, mainly for goog.require / goog.provide /
     // goog.module).
     document.write(
-        '<script src="' + options.root + '/closure/goog/base.js"></script>');
+        '<script src="' + options.root +
+            'build/src/closure/goog/base.js"></script>');
 
     // Prevent spurious transpilation warnings.
     document.write('<script>goog.TRANSPILE = "never";</script>');
@@ -174,7 +175,7 @@
     for (let script, i = 0; script = scripts[i]; i++) {
       const fakeModuleName = 'script.' + script.replace(/[./]/g, "-");
       scriptDeps.push('  goog.addDependency(' +
-          quote('../../' + script) + ', [' + quote(fakeModuleName) +
+          quote('../../../../' + script) + ', [' + quote(fakeModuleName) +
           '], [' + requires.map(quote).join() + "], {'lang': 'es6'});\n");
       requires = [fakeModuleName];
     }
diff --git a/tsconfig.json b/tsconfig.json
index 12a91c8b0b3..f167444b358 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,7 @@
 {
   "include": [
     "core/**/*",  // N.B.: also pulls in closure/goog/goog.js if needed.
-    "closure/goog/goog.js",  // Just for ouptut directory structure.
+    "closure/**/*",  // Just for ouptut directory structure.
   ],
   "compilerOptions": {
     // Tells TypeScript to read JS files, as