diff --git a/src/common/validate/skeleton.js b/src/common/validate/skeleton.js
new file mode 100644
index 000000000..24c43adaa
--- /dev/null
+++ b/src/common/validate/skeleton.js
@@ -0,0 +1,48 @@
+define([
+	"../create-error",
+	"./skeleton/fields-pos-map"
+], function( createError, validateSkeletonFieldsPosMap ) {
+
+/**
+ * validateSkeleton( skeleton )
+ *
+ * skeleton: Assume `j` has already been converted into a localized hour field.
+ */
+return function validateSkeleton( skeleton ) {
+	var last,
+
+		// Using easier to read variable.
+		fieldsPosMap = validateSkeletonFieldsPosMap;
+
+	// "The fields are from the Date Field Symbol Table in Date Format Patterns"
+	// Ref: http://www.unicode.org/reports/tr35/tr35-dates.html#availableFormats_appendItems
+	// I.e., check for invalid characters.
+	skeleton.replace( /[^GyYuUrQqMLlwWEecdDFghHKkmsSAzZOvVXx]/, function( field ) {
+		throw createError(
+			"E_INVALID_OPTIONS", "Invalid field `{field}` of skeleton `{skeleton}`",
+			{
+				field: field,
+				skeleton: skeleton
+			}
+		);
+	});
+
+	// "The canonical order is from top to bottom in that table; that is, yM not My".
+	// http://www.unicode.org/reports/tr35/tr35-dates.html#availableFormats_appendItems
+	// I.e., check for invalid order.
+	skeleton.split( "" ).every(function( field ) {
+		if ( fieldsPosMap[ field ] < last ) {
+			throw createError(
+				"E_INVALID_OPTIONS", "Invalid order `{field}` of skeleton `{skeleton}`",
+				{
+					field: field,
+					skeleton: skeleton
+				}
+			);
+		}
+		last = fieldsPosMap[ field ];
+		return true;
+	});
+};
+
+});
diff --git a/src/common/validate/skeleton/fields-pos-map.js b/src/common/validate/skeleton/fields-pos-map.js
new file mode 100644
index 000000000..65f380530
--- /dev/null
+++ b/src/common/validate/skeleton/fields-pos-map.js
@@ -0,0 +1,16 @@
+define(function() {
+
+/**
+ * Create a map between the skeleton fields and their positions, e.g.,
+ * {
+ *   G: 0
+ *   y: 1
+ *   ...
+ * }
+ */
+return "GyYuUrQqMLlwWEecdDFghHKkmsSAzZOvVXx".split( "" ).reduce(function( memo, item, i ) {
+	memo[ item ] = i;
+	return memo;
+}, {});
+
+});
diff --git a/src/date/expand-pattern.js b/src/date/expand-pattern.js
index ce9729cd5..34eefb3cf 100644
--- a/src/date/expand-pattern.js
+++ b/src/date/expand-pattern.js
@@ -1,8 +1,9 @@
 define([
-	"../common/format-message",
 	"../common/create-error/invalid-parameter-value",
+	"../common/format-message",
+	"../common/validate/skeleton",
 	"./expand-pattern/get-best-match-pattern"
-], function( formatMessage, createErrorInvalidParameterValue,
+], function( createErrorInvalidParameterValue, formatMessage, validateSkeleton,
 	dateExpandPatternGetBestMatchPattern ) {
 
 /**
@@ -51,6 +52,8 @@ return function( options, cldr ) {
 				return cldr.supplemental.timeData.preferred();
 			});
 
+			validateSkeleton( skeleton );
+
 			// Try direct map (note that getBestMatchPattern handles it).
 			// ... or, try to "best match" the whole skeleton.
 			result = getBestMatchPattern(
diff --git a/test/unit/date/expand-pattern.js b/test/unit/date/expand-pattern.js
index f5c58a8a0..935200474 100644
--- a/test/unit/date/expand-pattern.js
+++ b/test/unit/date/expand-pattern.js
@@ -43,36 +43,36 @@ QUnit.test( "should expand {skeleton: \"<skeleton>\"}", function( assert ) {
 	assert.expandPattern( de, { skeleton: "jmm" }, "HH:mm" );
 	assert.expandPattern( ru, { skeleton: "jmm" }, "H:mm" );
 
-	// Best match the whole skeleton.
+	// Best matches the whole skeleton.
 	assert.expandPattern( en, { skeleton: "hhmm" }, "hh:mm a" );
 	assert.expandPattern( en, { skeleton: "HHmm" }, "HH:mm" );
 	assert.expandPattern( en, { skeleton: "EHmss" }, "E HH:mm:ss" );
 	assert.expandPattern( en, { skeleton: "yy" }, "yy" );
 	assert.expandPattern( de, { skeleton: "yMMMMd" }, "d. MMMM y" );
 	assert.expandPattern( de, { skeleton: "MMMM" }, "LLLL" );
-	assert.expandPattern( de, { skeleton: "MMMMy" }, "MMMM y" );
+	assert.expandPattern( de, { skeleton: "yMMMM" }, "MMMM y" );
 	assert.expandPattern( de, { skeleton: "EEEE" }, "cccc" );
 	assert.expandPattern( de, { skeleton: "cccc" }, "cccc" );
-	assert.expandPattern( de, { skeleton: "EEEEMMMMd" }, "EEEE, d. MMMM" );
-	assert.expandPattern( de, { skeleton: "ccccMMMMd" }, "EEEE, d. MMMM" );
+	assert.expandPattern( de, { skeleton: "MMMMEEEEd" }, "EEEE, d. MMMM" );
+	assert.expandPattern( de, { skeleton: "MMMMccccd" }, "EEEE, d. MMMM" );
 	assert.expandPattern( de, { skeleton: "HHmm" }, "HH:mm" );
 	assert.expandPattern( de, { skeleton: "EEEEHHmm" }, "EEEE, HH:mm" );
 	assert.expandPattern( de, { skeleton: "EEEEHmm" }, "EEEE, HH:mm" );
 	assert.expandPattern( de, { skeleton: "ccccHmm" }, "EEEE, HH:mm" );
 	assert.expandPattern( ru, { skeleton: "yMMMMd" }, "d MMMM y 'г'." );
 	assert.expandPattern( ru, { skeleton: "MMMM" }, "LLLL" );
-	assert.expandPattern( ru, { skeleton: "MMMMy" }, "LLLL y 'г'." );
+	assert.expandPattern( ru, { skeleton: "yMMMM" }, "LLLL y 'г'." );
 	assert.expandPattern( ru, { skeleton: "EEEE" }, "cccc" );
 	assert.expandPattern( ru, { skeleton: "cccc" }, "cccc" );
-	assert.expandPattern( ru, { skeleton: "EEEEMMMMd" }, "cccc, d MMMM" );
-	assert.expandPattern( ru, { skeleton: "ccccMMMMd" }, "cccc, d MMMM" );
+	assert.expandPattern( ru, { skeleton: "MMMMEEEEd" }, "cccc, d MMMM" );
+	assert.expandPattern( ru, { skeleton: "MMMMccccd" }, "cccc, d MMMM" );
 	assert.expandPattern( ru, { skeleton: "HHmm" }, "HH:mm" );
 	assert.expandPattern( ru, { skeleton: "EEEEHHmm" }, "EEEE HH:mm" );
 	assert.expandPattern( ru, { skeleton: "EEEEHmm" }, "EEEE HH:mm" );
 	assert.expandPattern( ru, { skeleton: "ccccHHmm" }, "EEEE HH:mm" );
 	assert.expandPattern( ru, { skeleton: "ccccHmm" }, "EEEE HH:mm" );
 
-	// Best match the date and time parts individually then combine together.
+	// Best matches the date and time parts individually then combine them together.
 	assert.expandPattern( en, { skeleton: "GyMMMEdhms" }, "E, MMM d, y G, h:mm:ss a" );
 	assert.expandPattern( en, { skeleton: "MMMMEdhm" }, "E, MMMM d 'at' h:mm a" );
 	assert.expandPattern( en, { skeleton: "MMMMh" }, "LLLL 'at' h a" );
@@ -80,6 +80,25 @@ QUnit.test( "should expand {skeleton: \"<skeleton>\"}", function( assert ) {
 	assert.expandPattern( ru, { skeleton: "MMMMEdhm" }, "ccc, d MMMM, h:mm a" );
 });
 
+QUnit.test( "should throw exception on invalid skeletons", function( assert ) {
+	// Invalid characters.
+	assert.throws(function() {
+		expandPattern({ skeleton: "MMM d" }, en );
+	});
+	assert.throws(function() {
+		expandPattern({ skeleton: "MM/dd" }, en );
+	});
+
+	// Invalid order.
+	assert.throws(function() {
+		expandPattern({ skeleton: "dM" }, en );
+	});
+	assert.throws(function() {
+		expandPattern({ skeleton: "My" }, en );
+		expandPattern({ skeleton: "MMMy" }, en );
+	});
+});
+
 QUnit.test( "should expand {date: \"(full, ...)\"}", function( assert ) {
 	assert.expandPattern( en, { date: "full" }, "EEEE, MMMM d, y" );
 });