Prior to the late 1960s second language acquisition was thought to be a relatively uninteresting phenomenon; it involved transferring grammatical properties already activated in the first language (L 1) onto second language (L 2) vocabulary. Successful L 2 learners were those who could capitalise on the similarities between the L 1 and the L 2, and eradicate the differences; and successful language teaching involved training learners to overcome the L 1-L 2 differences. Today, perceptions of second language acquisition are more sophisticated and nuanced. Second language acquisition researchers are interested in questions bearing not only on the influence of the L 1, but also on the degree of systematicity in L 2 development, the role that L 1, but also on the degree of systematicity in L 2 development, the role that conscious knowledge plays, the sources of variability in second language speaker performance, the ultimate levels of success achieved by L 2 learners of different ages, and individual differences between learners. The purpose of this article is to present what the authors believe to be some of the key issues which characterise current second language acquisition research, and to consider those issues within the specific context of the acquisition of French as second language.