The Germanic languages display cross-linguistic variation with respect to whether predicative adjectives agree. This paper attempts to determine which component of the grammar is responsible for this variation. In order to do so, it examines three different options: the variation has a lexical source, a syntactic source, or is due to an interaction between syntax and morphology. The conclusion the paper reaches is that the variation is either situated in the lexicon or has a morphosyntactic source. A purely syntactic source will, however, be excluded
