Wrap teasers in a div (simple taxonomy page, no views)
Using template.php and hook_preprocess_page()

function THEMENAME_preprocess_page(&amp;$variables) {
  if (arg(0) == 'taxonomy' &amp;&amp; arg(1) == 'term' &amp;&amp; is_numeric(arg(2))) {
    $variables['page']['content']['system_main']['nodes']['#prefix'] = '&lt;div class="here-is-your-div"&gt;';
    $variables['page']['content']['system_main']['nodes']['#suffix'] = '&lt;/div&gt;';
  }
}


So what this does is checks if the URLs match the condition /taxonomy/term/%term-id then if it's satisfied then it adds a prefix and a suffix that are to be rendered by &lt;?php print render($page['content']); ?&gt;.