Frisian belongs to the set of Germanic languages that show agreement between the complementizer and the subject, albeit in a very modest way. This paper compares two approaches to the nature of agreeing complementizers: a clitic analysis and an inflection analysis. Arguments are presented for the latter. Within the context of a more general theory of agreement, we discuss the nature of the dependency relation between the complementizer and the subject, claiming that it involves a limited form of incorporation of the subject into the complementizer. This analysis also makes an agreement approach to pro-drop in Frisian feasible. Finally we demonstrate that Frisian belongs to the subset of complementizer languages that have double agreement forms, i.e. the forms for non-inverted and inverted verbs are not entirely identical.