L2 lexical development does not happen in a vacuum. By definition, it takes place against the background of lexical development in at least one other language. The present chapter begins with some thoughts on the nature of the challenge posed by L1 and L2 lexical development in different circumstances. Thereafter, it attempts to summarize current perspectives on L1 lexical development, touching on some of the theoretical issues that arise in this context. The chapter then concludes with a few preliminary words on the question of the degree of similarity/difference between L1 and L2 lexical development.

The lexical challenge

Clearly, the lexicon develops and expands in a variety of circumstances under the impetus of a variety of stimuli – for example, in infancy and early childhood, during schooling as L1 literacy skills are established, in the course of the ‘naturalistic’ acquisition of an L2, and in the framework of formal L2 instruction. This list is far from exhaustive; indeed, since language is so all-pervasive in human life, and since lexis is so all-pervasive in language, there must be few situations which do not offer opportunities for lexical development of one kind or another.

Certainly it would be entirely mistaken to believe that this process is confined to what happens ‘at the mother's knee’ or in the primaryschool classroom – even as far as L1 lexical acquisition is concerned. Thus, for example, a number of researchers have written about the vast quantity of new slang expressions that are taken on board in the teenage years and which serve to define group membership (see, e.g., Britton, 1970; E. Nelson and Rosenbaum, 1968; Schwartz and Merten, 1967).