“…It is well established that auxiliary selection in periphrastic perfect constructions is characterized by extensive and subtle crosslinguistic variation (see, e.g., Aranovich 2007, McFadden 2007 for recent discussion). We take it to be a reasonable methodological assumption that this variation is not arbitrary, but can be related to independently observable properties of the languages in For helpful discussion and comments on this and earlier versions of the work presented here, we would like to thank two anonymous Linguistic Inquiry reviewers, Elena Anagnostopoulou, Jonny Butler, Dave Embick, Susann Fischer, Sabine Iatridou, Tony Kroch, Winfried Lechner, Eric Reuland, Florian Schäfer, Sandhya Sundaresan, and audiences at the Penn Linguistics Colloquium 29, the West Coast Conference on Formal Linguistics 24 and 25, the Workshop on Technology in the Humanities, the Comparative Germanic Syntax Workshop 20 and 21, Diachronic Generative Syntax 9, and the 5th and 6th York-Newcastle-Holland Symposia on the History of English Syntax.…”