The purpose of my Master thesis is to shed some light on how the existence of multiple ethnic identities within state borders may be associated with regime stability. My argument si that political institutions do matter, both in shaping the salience of ethnic identities, and in creating motives and opportunities for a possible ethnic mobilization. In this regard, exclusion of ethnic groups from political power is an important determinant of frustration. I propose that ethno-political exclusion may threaten the duration of political structures, but that this in turn is dependent on regime type. I find that exclusion of ethnic groups from power severeley heightens the risk of instability in democracies, but that is does not have an impact for the stability of autocracies and inconsitent regimes. See publications for MA-thesis, dataset, and coding on ethnic groups in power.