diff --git a/packager/mpd/base/mpd_builder.cc b/packager/mpd/base/mpd_builder.cc
index 3f8ed98ef9..7ccdaf7e2d 100644
--- a/packager/mpd/base/mpd_builder.cc
+++ b/packager/mpd/base/mpd_builder.cc
@@ -35,6 +35,8 @@ using xml::AdaptationSetXmlNode;
 
 namespace {
 
+const int kAdaptationSetGroupNotSet = -1;
+
 std::string GetMimeType(const std::string& prefix,
                         MediaInfo::ContainerType container_type) {
   switch (container_type) {
@@ -565,7 +567,8 @@ AdaptationSet::AdaptationSet(uint32_t adaptation_set_id,
       representation_counter_(counter),
       id_(adaptation_set_id),
       lang_(lang),
-      mpd_options_(mpd_options) {
+      mpd_options_(mpd_options),
+      group_(kAdaptationSetGroupNotSet) {
   DCHECK(counter);
 }
 
@@ -664,6 +667,9 @@ xml::ScopedXmlPtr<xmlNode>::type AdaptationSet::GetXml() {
 
   if (picture_aspect_ratio_.size() == 1)
     adaptation_set.SetStringAttribute("par", *picture_aspect_ratio_.begin());
+
+  if (group_ >= 0)
+    adaptation_set.SetIntegerAttribute("group", group_);
   return adaptation_set.PassScopedPtr();
 }
 
diff --git a/packager/mpd/base/mpd_builder.h b/packager/mpd/base/mpd_builder.h
index 6176b62406..d4794e1a37 100644
--- a/packager/mpd/base/mpd_builder.h
+++ b/packager/mpd/base/mpd_builder.h
@@ -175,6 +175,15 @@ class AdaptationSet {
   ///         NULL ScopedXmlPtr.
   xml::ScopedXmlPtr<xmlNode>::type GetXml();
 
+  /// Sets the AdaptationSet@group attribute.
+  /// Passing a negative value to this method will unset the attribute.
+  /// Note that group=0 is a special group, as mentioned in the DASH MPD
+  /// specification.
+  /// @param group_number is the value of AdaptatoinSet@group.
+  void set_group(int group_number) {
+    group_ = group_number;
+  }
+
   // Must be unique in the Period.
   uint32_t id() const { return id_; }
 
@@ -187,6 +196,7 @@ class AdaptationSet {
                            CheckAdaptationSetAudioContentType);
   FRIEND_TEST_ALL_PREFIXES(CommonMpdBuilderTest,
                            CheckAdaptationSetTextContentType);
+  FRIEND_TEST_ALL_PREFIXES(CommonMpdBuilderTest, SetAdaptationSetGroup);
 
   /// @param adaptation_set_id is an ID number for this AdaptationSet.
   /// @param representation_counter is a Counter for assigning ID numbers to
@@ -212,6 +222,11 @@ class AdaptationSet {
   const std::string lang_;
   const MpdOptions& mpd_options_;
 
+  // The group attribute for the AdaptationSet. If the value is negative,
+  // no group number is specified.
+  // Note that group 0 is a special group number.
+  int group_;
+
   // Video widths and heights of Representations. Note that this is a set; if
   // there is only 1 resolution, then @width & @height should be set, otherwise
   // @maxWidth & @maxHeight should be set for DASH IOP.
diff --git a/packager/mpd/base/mpd_builder_unittest.cc b/packager/mpd/base/mpd_builder_unittest.cc
index 8d683072bf..b7c45de722 100644
--- a/packager/mpd/base/mpd_builder_unittest.cc
+++ b/packager/mpd/base/mpd_builder_unittest.cc
@@ -325,6 +325,24 @@ class TimeShiftBufferDepthTest : public SegmentTemplateTest {
   }
 };
 
+// Verify that AdaptationSet@group can be set and unset.
+TEST_F(CommonMpdBuilderTest, SetAdaptationSetGroup) {
+  base::AtomicSequenceNumber sequence_counter;
+  AdaptationSet adaptation_set(
+      kAnyAdaptationSetId, "", MpdOptions(), &sequence_counter);
+  adaptation_set.set_group(1);
+
+  xml::ScopedXmlPtr<xmlNode>::type xml_with_group(adaptation_set.GetXml());
+  EXPECT_NO_FATAL_FAILURE(
+      ExpectAttributeEqString("group", "1", xml_with_group.get()));
+
+  // Unset by passing a negative value.
+  adaptation_set.set_group(-1);
+  xml::ScopedXmlPtr<xmlNode>::type xml_without_group(adaptation_set.GetXml());
+  EXPECT_NO_FATAL_FAILURE(
+      ExpectAttributeNotSet("group", xml_without_group.get()));
+}
+
 // Verify that Representation::Init() works with all "required" fields of
 // MedieInfo proto.
 TEST_F(CommonMpdBuilderTest, ValidMediaInfo) {