Complementing Bart Geurts' (2000) review of the same book, Ken Drozd's Learnability and linguistic performance points out several serious problems with the L1 acquisition research programme of Crain & Thornton (1998). Drozd's objections are so clearly stated that there is little I can add. Nonetheless, I will attempt to flesh out some of his more general points by examining more closely a specific case, namely the experiments in Crain, Thornton, Boster, Conway, Lillo-Martin & Woodams (1996) which focused on normal preschool children's understanding of simple universally quantified sentences.