This study deals with the complementation of verbs in Icelandic. The main emphasis is on clausal complements of verbs and the syntactic rules that operate in and on such complements. This study is written with two kinds of readers in mind. First, it is written for the theoretical linguist who is looking for phenomena of general theoretical interest, i.e. facts about Icelandic syntax that bear on the question what an adequate general linguistic theory must be like and hence shed some light on the nature of human language. Second, the study is also written with a different kind of reader in mind, namely a reader who is interested in Icelandic syntax in particular, perhaps from a more descriptive point of view.