Who supports secession in a multiethnic country? What factors lead to secessionist or separatist attitudes? Despite the substantial interest in secessionist movements, the micro‐level factors and dynamics behind mass support for secession have been understudied. Using original and comprehensive data derived from two public opinion surveys, conducted in 2011 and 2013 with nationwide, representative samples, this study investigates the determinants of separatist attitudes among Turkey's Kurds. The empirical results show that perceptions of discrimination, ideological factors (i.e. a left‐right division and partisanship), region and religious sect do affect support for secession. Our findings provide strong support for the grievance theory and, further, show that ideology is an important factor. However, the results call into question arguments drawing attention to the role of modernisation (i.e. socio‐economic status) and of religiosity. The study also discusses some practical implications of the empirical findings.