diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 258ad2e4..a633727e 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -160,7 +160,7 @@ def tag_link(type, tag, link_class=nil)
       when :venue then venues_path(:tag => tag.name)
       end
 
-    link_classes = [link_class]
+    link_classes = [link_class, "p-category"]
     link_classes << "external #{tag.machine_tag[:namespace]} #{tag.machine_tag[:predicate]}" if tag.machine_tag[:url]
 
     link_to escape_once(tag.name), (tag.machine_tag[:url] || internal_url), :class => link_classes.compact.join(' ')
diff --git a/app/helpers/time_range_helper.rb b/app/helpers/time_range_helper.rb
index f166b378..f0a5e7ea 100644
--- a/app/helpers/time_range_helper.rb
+++ b/app/helpers/time_range_helper.rb
@@ -89,14 +89,14 @@ def to_s
 
     # Combine the pieces
     results = []
-    results << %Q|<abbr class="dtstart" title="#{@start_time.strftime('%Y-%m-%dT%H:%M:%S')}">| if @format == :hcal
+    results << %Q|<time class="dtstart dt-start" title="#{@start_time.strftime('%Y-%m-%dT%H:%M:%S')}" datetime="#{@start_time.strftime('%Y-%m-%dT%H:%M:%S')}">| if @format == :hcal
     results << format_details_by_list(start_details, start_format_list)
-    results << %Q|</abbr>| if @format == :hcal
+    results << %Q|</time>| if @format == :hcal
     if end_format_list
       results << conjunction
-      results << %Q|<abbr class="dtend" title="#{@end_time.strftime('%Y-%m-%dT%H:%M:%S')}">| if @format == :hcal
+      results << %Q|<time class="dtend dt-end" title="#{@end_time.strftime('%Y-%m-%dT%H:%M:%S')}" datetime="#{@end_time.strftime('%Y-%m-%dT%H:%M:%S')}">| if @format == :hcal
       results << format_details_by_list(end_details, end_format_list)
-      results << %Q|</abbr>| if @format == :hcal
+      results << %Q|</time>| if @format == :hcal
     end
     results.join('').html_safe
   end
diff --git a/app/views/events/_item.html.erb b/app/views/events/_item.html.erb
index 5a7c3d76..ed9e9387 100644
--- a/app/views/events/_item.html.erb
+++ b/app/views/events/_item.html.erb
@@ -9,35 +9,35 @@ html_classes = "single_event"
 html_classes << " contentbar" if has_contentbar
 %>
 <div class="<%= html_classes %>">
-  <div class="vevent" itemscope itemtype="http://schema.org/Event">
-    <h1 class="summary" itemprop="name"><%= event.title %></h1>
+  <div class="vevent h-event" itemscope itemtype="http://schema.org/Event">
+    <h1 class="summary p-name" itemprop="name"><%= event.title %></h1>
     <meta itemprop="startDate" content="<%= event.start_time.to_time.iso8601 %>">
     <% if event.end_time %>
       <meta itemprop="endDate" content="<%= event.end_time.to_time.iso8601 %>">
     <% end %>
     <div class='date'><%= normalize_time(event) -%></div>
       <% unless event.venue.blank? %>
-      <div class="clearfix location vcard<%= " closed" if event.venue.closed? %>"  itemprop="location" itemscope itemtype="http://schema.org/Place">
+      <div class="clearfix location p-location h-card vcard<%= " closed" if event.venue.closed? %>"  itemprop="location" itemscope itemtype="http://schema.org/Place">
       <%= google_map event %>
-          <a class="url" href='<%= event.venue.new_record? ? "#" : venue_url(event.venue) %>'>
-            <span class='fn org' itemprop="name"><%= event.venue.title -%></span>
+          <a class="url u-url" href='<%= event.venue.new_record? ? "#" : venue_url(event.venue) %>'>
+            <span class='fn org p-name' itemprop="name"><%= event.venue.title -%></span>
           </a>
           <% if event.venue.closed? %><p class='closed_callout'>This venue is no longer open for business.</p><% end %>
-          <div class="adr" itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
+          <div class="adr p-adr h-adr" itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
           <% if !event.venue.street_address.blank? -%>
-          <div class="street-address" itemprop="streetAddress"><%= event.venue.street_address -%></div>
+          <div class="p-street-address" itemprop="streetAddress"><%= event.venue.street_address -%></div>
           <% end %>
           <% if !event.venue.locality.blank? -%>
-            <span class="locality" itemprop="addressLocality"><%= event.venue.locality -%></span><%= "," if event.venue.region.present? or event.venue.postal_code.present? or event.venue.country.present? %>
+            <span class="p-locality" itemprop="addressLocality"><%= event.venue.locality -%></span><%= "," if event.venue.region.present? or event.venue.postal_code.present? or event.venue.country.present? %>
             <% end -%>
             <% if !event.venue.region.blank? -%>
-            <span class="region" itemprop="addressRegion"><%= event.venue.region -%></span><%= "," if event.venue.country.present? and not event.venue.postal_code.present? %>
+            <span class="p-region" itemprop="addressRegion"><%= event.venue.region -%></span><%= "," if event.venue.country.present? and not event.venue.postal_code.present? %>
             <% end -%>
             <% if !event.venue.postal_code.blank? -%>
-            <span class="postal-code"  itemprop="postalCode"><%= event.venue.postal_code -%></span><%= "," if  event.venue.country.present? %>
+            <span class="p-postal-code"  itemprop="postalCode"><%= event.venue.postal_code -%></span><%= "," if  event.venue.country.present? %>
             <% end -%>
             <% if !event.venue.country.blank? -%>
-            <span class='country-name'><%= event.venue.country -%></span>
+            <span class='p-country-name'><%= event.venue.country -%></span>
             <% end -%>
             <% if event.venue && event.venue.has_full_address? -%>
             (<a href='<%=google_maps_url(event.venue.full_address) -%>'>map</a>)
@@ -55,7 +55,7 @@ html_classes << " contentbar" if has_contentbar
             <% end -%>
 
             <% unless event.venue_details.blank? -%>
-            <p>
+            <p class="p-description">
               <%= format_description(event.venue_details) %>
             </p>
             <% end -%>
@@ -67,14 +67,14 @@ html_classes << " contentbar" if has_contentbar
     <% unless event.url.blank? -%>
       <h3>Website</h3>
       <div class="website">
-        <%= link_to "#{truncate(event.url, :length => 128)}", h(event.url), :class => "url", :rel => "nofollow", 
+        <%= link_to "#{truncate(event.url, :length => 128)}", h(event.url), :class => "url u-url", :rel => "nofollow", 
         :itemprop => "url" %>
       </div>
     <% end -%>
 
     <% unless event.description.blank? -%>
     <h3>Description</h3>
-    <div class="description" itemprop="description">
+    <div class="description e-description" itemprop="description">
       <%= format_description(event.description) %>
     </div>
     <% end -%>
diff --git a/app/views/events/_list_item.html.erb b/app/views/events/_list_item.html.erb
index 8bbd45cd..c4c2157d 100644
--- a/app/views/events/_list_item.html.erb
+++ b/app/views/events/_list_item.html.erb
@@ -4,7 +4,7 @@ opts ||= {}
 opts[:dates] = opts.has_key?(:dates) ? opts[:dates] : true
 show_year ||= false
 %>
-<div class='vevent'>
+<div class='vevent h-event'>
   <% date_class = (opts[:dates]==false || !new_day) ? ' hidden' : '' -%>
   <div class='list_date<%=date_class%>'>
     <div class='day_of_week'><%= today_tomorrow_or_weekday(event) %></div>
@@ -14,20 +14,20 @@ show_year ||= false
     <% end %>
   </div>
   <div class='list_content'>
-    <a class='summary' href='<%= url_for event_url(event) %>'><%= event.title %></a>
+    <a class='summary p-name u-url' href='<%= url_for event_url(event) %>'><%= event.title %></a>
     <div>
     <%= normalize_time(event, :context => event.start_time.to_date) -%>
     <% if event.venue && !event.venue.title.blank? %>
-      <br/><a class='location' href='<%= url_for venue_url(event.venue) %>'><%= event.venue.title -%></a>
+      <br/><a class='location p-location h-card' href='<%= url_for venue_url(event.venue) %>'><%= event.venue.title -%></a>
     <% end -%>
     </div>
     <% if !event.description.blank? %>
-      <div class='description'>
+      <div class='description e-description'>
         <%= format_description(event.description) -%>
       </div>
     <% end -%>
     <% if !event.url.blank? -%>
-      <%= link_to "Website", h(event.url), :class => "url", :rel => "nofollow" -%>
+      <%= link_to "Website", h(event.url), :class => "url u-url", :rel => "nofollow" -%>
     <% end -%>
   </div>
 </div>
diff --git a/app/views/events/_table.html.erb b/app/views/events/_table.html.erb
index 2b3f43c4..94ac998b 100644
--- a/app/views/events/_table.html.erb
+++ b/app/views/events/_table.html.erb
@@ -31,7 +31,7 @@ rowspans = calculate_rowspans(events)
   <tbody>
     <% unless events.size==0 %>
       <% events.each_with_index do |event, index| %>
-        <tr class='vevent'>
+        <tr class='vevent h-event'>
           <% if rowspans[index] > 0 %>
           <td class='date' rowspan="<%=rowspans[index]%>">
             <div class='day_of_week <%= today_tomorrow_or_weekday(event).downcase -%>'>
@@ -42,18 +42,18 @@ rowspans = calculate_rowspans(events)
           </td>
           <% end %>
           <td class='event_summary'>
-            <a class='summary' href='<%= url_for event_url(event) %>' name='<%= "event-#{event.id}" %>' id='<%= "event-#{event.id}" %>'><%= event.title %></a><br />
+            <a class='summary p-name u-url' href='<%= url_for event_url(event) %>' name='<%= "event-#{event.id}" %>' id='<%= "event-#{event.id}" %>'><%= event.title %></a><br />
             <%= normalize_time(event, :context => event.start_time.to_date) -%>
             <% if event.venue && !event.venue.title.blank? %>
-              <a class='location' href='<%= url_for venue_url(event.venue) %>'><%= event.venue.title -%></a>
+              <a class='location p-location h-card' href='<%= url_for venue_url(event.venue) %>'><%= event.venue.title -%></a>
             <% end -%>
             <% if !event.description.blank? %>
-              <div class='description'>
+              <div class='description e-description'>
                 <%= format_description(event.description) -%>
               </div>
             <% end -%>
             <% if !event.url.blank? -%>
-              <%= link_to "Website", event.url, :class => "url", :rel => "nofollow" -%>
+              <%= link_to "Website", event.url, :class => "url u-url", :rel => "nofollow" -%>
             <% end -%>
           </td>
         </tr>
diff --git a/spec/helpers/time_range_helper_spec.rb b/spec/helpers/time_range_helper_spec.rb
index b68e9bbd..3148acc5 100644
--- a/spec/helpers/time_range_helper_spec.rb
+++ b/spec/helpers/time_range_helper_spec.rb
@@ -12,17 +12,17 @@
   tests = [
     # comment, end_time, results_without_context, results_with_context
     [ "start time only", nil,
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 at 9am</abbr>",
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">9am</abbr>"],
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 at 9am</time>",
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">9am</time>"],
     [ "same day & am-pm", DateTime.new(2008, 4, 1, 11, 00),
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 from 9</abbr>&ndash;<abbr class=\"dtend\" title=\"2008-04-01T11:00:00\">11am</abbr>",
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">9</abbr>&ndash;<abbr class=\"dtend\" title=\"2008-04-01T11:00:00\">11am</abbr>" ],
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 from 9</time>&ndash;<time class=\"dtend dt-end\" title=\"2008-04-01T11:00:00\" datetime=\"2008-04-01T11:00:00\">11am</time>",
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">9</time>&ndash;<time class=\"dtend dt-end\" title=\"2008-04-01T11:00:00\" datetime=\"2008-04-01T11:00:00\">11am</time>" ],
     [ "same day, different am-pm", DateTime.new(2008, 4, 1, 13, 30),
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 from 9am</abbr>&ndash;<abbr class=\"dtend\" title=\"2008-04-01T13:30:00\">1:30pm</abbr>",
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">9am</abbr>&ndash;<abbr class=\"dtend\" title=\"2008-04-01T13:30:00\">1:30pm</abbr>" ],
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 from 9am</time>&ndash;<time class=\"dtend dt-end\" title=\"2008-04-01T13:30:00\" datetime=\"2008-04-01T13:30:00\">1:30pm</time>",
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">9am</time>&ndash;<time class=\"dtend dt-end\" title=\"2008-04-01T13:30:00\" datetime=\"2008-04-01T13:30:00\">1:30pm</time>" ],
     [ "different days", DateTime.new(2009, 4, 1, 13, 30),
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 at 9am</abbr> through <abbr class=\"dtend\" title=\"2009-04-01T13:30:00\">Wednesday, April 1, 2009 at 1:30pm</abbr>",
-      "<abbr class=\"dtstart\" title=\"2008-04-01T09:00:00\">9am</abbr> through <abbr class=\"dtend\" title=\"2009-04-01T13:30:00\">Wednesday, April 1, 2009 at 1:30pm</abbr>" ]
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">Tuesday, April 1, 2008 at 9am</time> through <time class=\"dtend dt-end\" title=\"2009-04-01T13:30:00\" datetime=\"2009-04-01T13:30:00\">Wednesday, April 1, 2009 at 1:30pm</time>",
+      "<time class=\"dtstart dt-start\" title=\"2008-04-01T09:00:00\" datetime=\"2008-04-01T09:00:00\">9am</time> through <time class=\"dtend dt-end\" title=\"2009-04-01T13:30:00\" datetime=\"2009-04-01T13:30:00\">Wednesday, April 1, 2009 at 1:30pm</time>" ]
   ]
 
   [nil, Date.new(2008, 4, 1)].each do |context_date|