This article re-examines the question of what makes some grammatical structures more difficult to learn than others, arguing that this question can only be properly understood and investigated with reference to the distinction between implicit and explicit knowledge of a second language. Using a battery of tests that were designed to measure…

Explores ways of measuring implicit and explicit second language (L2) knowledge and examines the relationship between these measures and measures of general language proficiency. Factor analysis revealed a two-factor solution, reflecting a clear distinction between measures that incorporated a time constraint and those that did not. (Author/VWL)