I-IV -- Table of Contents -- Introduction -- Bibliography -- Raising Questions: Formal and Functional Aspects of the Acquisition of Wh-Questions in German -- Possible Domains for Individual Variation in Early Developmental Stages -- Variations on "Variation": On the Acquisition of Complementizers in German -- Learnability Meets Development: The Case of Pro-Drop -- A Theory of Null Objects and the Development of a Brazilian Child Grammar -- Activating Passives in Child Grammar -- Variation in Grammar and First Language Acquisition: A New Concept of Parameter in Universal Grammar -- Intermodular Synchronization: On the Role of Morphology in the Normal and Impaired Acquisition of a Verb-Second Language -- How Do Children Cope with Variation in the Input? The Case of German Plurals and Compounding -- Variation in the Acquisition of German Plural Morphology by Second Language Learners -- Inference and Learnability in Second Language Acquisition: Universals vs. Language-Specific Phenomena in the Domain of Idiomatic Expression -- List of Contributors