Is Frisian becoming more like Dutch? This dissertation investigates changes in the Frisian grammar as a result of language contact with Dutch. Three grammatical constructions with verbs are investigated, which are similar but not exactly the same in Frisian and Dutch: (i) endings on infinitival verbs, (ii) nouns that form one word with a verb (e.g. messeslypje, “knife-sharpening”), and (iii) the absentive, a grammatical construction which expresses that someone is absent (e.g. Hy is te fiskjen, “He is off fishing”). It is proposed that the kind of change that is found is not only influenced by language-external (i.e., social) factors (for example, the extent to which a speaker of Frisian has a positive attitude towards Dutch) but crucially also by language-internal factors: the structure of the grammatical construction partly determines what the formal change can look like. We find, for example, that if the linguistic structures of the Frisian and Dutch constructions are very different, it is likely that the “Dutch” version is accepted in addition to a Frisian version. That is, the speaker can express this construction in two ways: the original Frisian way, and the "innovative" way, that is the way which is more similar to Dutch. To give an example: many speakers of Frisian who use the Frisian pattern Hy is te fiskjen (lit. “He is to fishing”, meaning “He is off fishing”) also use the "Dutch" pattern Hy is fiskjen (lit. “He is fishing”, meaning “He is off fishing”). The latter is an innovation that results from language contact with Dutch.