The continental West Germanic dialect continuum roughly encompasses the territory of modern-day Germany, Austria, the German-speaking part of Switzerland, the Netherlands, the northern half of Belgium (Flanders), Liechtenstein, Luxembourg and South Tyrol, in northern Italy. The dialectal varieties in this region differ and are classified on the basis of phonological, morphological, and lexical distinctions. The varieties of Netherlandish and Frisian represent the northernmost part of the continuum. The remaining area, in which Standard German can be viewed as the high variety, is traditionally divided into subdialects utilizing consonantal and vocalic innovations, e.g., the High German consonant shift. The German dialects also differ in terms of noun case distinctions, plural verb morphology, and lexical variation.

This chapter discusses Complementizer Agreement (CA): agreement between the complementizer introducing an embedded finite clause and the subject of that embedded clause. CA is mainly found in Frisian and the nonstandard varieties of Dutch and German. This chapter discusses the morphological properties of CA, in particular the (defectivity of) its paradigm, the relation between the CA paradigm and the verbal agreement paradigm, and the relation between the agreement on the complementizer, clitics, and pro-drop. It also goes into the syntactic properties of CA: its distribution in the left periphery and the relation between the subject and the complementizer.