Against the background of the past half century’s typological and generative work on comparative syntax, this volume brings together 16 papers considering what we have learned and may still be able to learn about the nature and extent of syntactic variation. More specifically, it offers a multi-perspective critique of the Principles and Parameters approach to syntactic variation, evaluating the merits and shortcomings of the pre-Minimalist phase of this enterprise and considering and illustrating the possibilities opened up by recent empirical and theoretical advances. Contributions focus on four central topics: firstly, the question of the locus of variation, whether the attested variation may plausibly be understood in parametric terms and, if so, what form such parameters might take; secondly, the fate of one of the most prominent early parameters, the Null Subject Parameter; thirdly, the matter of parametric clusters more generally; and finally, acquisition issues.