E ver since our student years, Dan Slobin has repeatedly demonstrated to all of us the indis-pensable role of comparative research in the study of language acquisition, showing us the way in his pioneering and persistent search for universal vs. variable aspects of child language. Although his initial aim was to generalize claims about universal mechanisms of language acquisition in the face of wide linguistic variation, evidence recurrently showed more and deeper crosslinguistic differences in child language over the years. This evidence, which was at rst surprising and somewhat embarrassing, constituted the rst step toward recent proposals suggesting that language particulars can massively or subtly inuence cognitive functioning in many ways.