Abstract: Do international election observers deter or spur violence after election day? This article argues that only when conceptually and empirically distinguishing between violence by governments and opposition groups, can we assess the impact of international election observation. Disaggregating post-electoral violence uncovers that observers can deter governments from using force, but they have the opposite effect on opposition groups. When expecting criticism from observers, opposition leaders can easily deny their responsibility for violence by individual party militants, while weaponry and official insignia betray police and military involvement in violence and force the government to bear command responsibility. Governments also anticipate higher international costs for engaging in post-electoral violence than opposition groups, which are not usually targets of international punishment. On the other hand, international election observers unintentionally incite opposition groups to organize violence, as oppo- sition groups seek to benefit from international attention and support that come with the presence of observers. Observers’ exposure of fraud reverses this differential effect: because governments expect international costs for election rigging anyway, observers cannot deter repression after highly fraudulent elections. But their alertness to electoral malpractice alleviates opposition groups’ incentives for post-electoral violence. Using data on 230 state-wide elections in Africa from 1990 to 2009, the analysis supports the observable implications of this argument. The findings of this article imply that international election observation missions make the post-electoral environment more peaceful when it comes to government repression after non-fraudulent elections. But observers ought to develop greater local expertise to identify opposition grievances before these groups resort to violence and be attentive to the possibility of increased repression after exposing cheating.