Online communication is often seen to promote audience fragmentation because it facilitates selective exposure and therefore is likely to divide audiences into sub-publics that hardly share common issues with other sub-publics. This study takes a micro-perspective on fragmentation by focusing on issue diversity in media items users have encountered in a particular week. Diversity was assessed via content analyses based on online diaries of 645 participants who recorded their media use concerning the German debates on climate change and federal elections. Findings show lower degrees of diversity for users of non-jour- nalistic online media than for users of journalistic mass media.