This book argues that syntactic parameters are set in a principled fashion on the basis of overt functional morphology. The main focus of the book is on the different positions of the finite verb in the Germanic SVO languages. In addition, other syntactic phenomena (null subjects, transitive expletive constructions and object shift) and other language families (Romance, Semitic and Slavic) are discussed. A common explanation for all of the discussed phenomena is proposed: If and only if the features for "person" are distinctively marked by the agreement morphology, the agreement affixes are listed separately in the lexicon and project phrases of their own in syntax where they attract the verb to the head positions and allow the specifier positions to be filled by various phonologically (un)realized elements. Special attention is given to issues of historical development and child language acquisition.