This dissertation investigates how syntactic parameters affect grammatical changes in a language contact situation. The empirical domain is grammatical changes in the Frisian verbal domain due to contact with Dutch. Three verbal constructions that show variation between Dutch and Frisian will be discussed. The first, the use of infinitival suffixes (-ən vs. -ə), is present in Frisian but absent in Dutch. The second and the third, noun incorporation patterns (oan’t messeslypje, “at the knife-sharpen, sharpening knives”) and the absentive (Hy is te fiskjen, “He is off fishing”) are found in both Frisian and Dutch but their properties differ. The thesis argues that the type of parameter that underlies these variation patterns between Frisian and Dutch (a Merge, Move or Spell-out parameter) is related to the kind of change that is found given the contact between the two languages.