In his review of Crain & Thornton's (C&T) (1998) ‘Investigations in Universal Grammar’ (IUG), Drozd raises the question of how models of children's linguistic competence relate to their linguistic performance. He highlights the use of processing limitations (PLs) to explain children's non-adultlike performance in most models of acquisition that adopt a Universal Grammar (UG) framework. Although the Modularity Matching (MM) model claims to avoid the need for performance-based constraints by assuming that children and adults operate with the same processing resources, Drozd argues that the model lacks predictive power.