Measurement of the electoral mobilization of ethnic parties has posed a considerable challenge to those performing comparative research on the political mobilization of ethnic groups. To address this issue, we propose indicators that estimate the electoral mobilization of ethnic parties by combining administrative and survey data. Specifically, we propose two measures: an absolute one, fully isolable from context, and a relative one, which corrects for turnouts. Furthermore, we show that a particular indicator based entirely on more widely available administrative data is valid when a narrow definition of ethnic parties is applied. Our indicators for the electoral mobilization of ethnic parties allow for valid comparisons across ethnic parties in different countries and regions at different points in time. We expect these new indicators to trigger further comparative studies on ethnic parties.