Information transparency is frequently heralded as a positive regime feature. However, does information transparency produce negative side effects such as increased terrorist activity? We theorize that freer transmission of information creates opportunities for radical dissidents to employ political violence to draw attention to their agendas. We build a theoretical argument connecting external (international) transparency to increases in transnational terrorism, and internal (domestic) transparency to increases in domestic terrorism. We find empirical support for our theory by analyzing the effects of measures of transparency on counts of terrorist attacks in as many as 144 countries for time periods as long as 1970 to 2006.