What keeps politicians together in a political party? Shared ideologies and policy goals go far towards answering that question in established democracies, but in Africa political parties hardly differ from each other in their policy programmes. This leaves party cohesion as an open question. In this study, I attempt to explain the decisions to stay with or defect from political parties made by Members of Parliament in Malawi – a sub-Saharan African country that clearly lacks a salient ideological cleavage. I show that re-election prospects and joining the government significantly determine patterns of party switching. I find mixed evidence that ethno-regional linkages account for loyalty, and no evidence that governing party politicians leave their parties to avoid blame for poor government performance. This study adds to the existing literature on party switching with theory and evidence from a new region.