Abstract: This paper discusses the two types of infinitives in Frisian: infinitives ending in -E (e.g. rinne “walk”) and infinitives ending in -EN (e.g. rinnen “walk”). It shows that their distribution can be accounted for by their different underlying syntactic structure: the -E infinitive has a fully verbal structure whereas the -EN infinitive has a flexible structure which always involves a DP. Moreover, I argue that the fact that the difference between the two forms is disappearing can be explained both by Dutch influence and by the fact that the structure of the infinitives already showed much overlap.