Published online by Cambridge University Press: 04 February 2010
The confirmatory nature of the empirical evidence used to establish UG effects in L2 development is considered. Specific issues are also raised concerning the internal validity of Epstein et al.'s findings. It is concluded that the role of UG in adult L2 development will only be established when researchers better understand the interaction between the development of UG-constrained structural knowledge and the development of overall L2 proficiency.