This monograph deals with the locative alternation in German, a change in the argument structure of verbs like spray and load. Like most argument structure changes, the alternation is both productive and constrained: new forms may be derived, but not from all candidate verbs. This raises a learnability problem: how can children determine, in the absence of negative evidence, which verbs participate in the alternation? The Locative Alternation in German tries to answer this question by providing an in-depth analysis of the conditions that verbs must meet in order to participate in the alternation. Most importantly, transitive verbs must allow speakers to presuppose the existence of their theme argument. This condition requires the theme to be incremental so that it can be conceived of as nonindividuated (or unbounded) when the verb is used in the alternative syntactic frame. The Nonindividuation Hypothesis splits locative verbs into two types, mass verbs (like spray) and count verbs (like load), and it predicts that children acquire the alternation first for mass verbs, whose theme must be a substance and so is nonindividuated by default. Support for this hypothesis is provided in the empirical part of the book, which also provides evidence against claims in the literature that children acquire the alternation by drawing on an innate Affectness Linking Rule.