This paper explores the history of Dutch credit unions (credietvereenigingen). Launched to provide SME credit, these credit unions gradually drifted away from their original aims, hereby increasingly targeting a wealthier echelon of clients at the expense of their poorer customers. In the end, they were squeezed out of business by new, government-supported SME banks and the big commercial banks. This study is devoted to understanding why this drift occurred and how this ultimately determined the development of these institutions. Thereby, it deepens our understanding of the similar challenges faced by present day social enterprises (most notably microcredit institutions) which may also succumb to mission drift, and hints to possible solutions in which such drift may be prevented.