The present paper aims to achieve a better understanding of the process of vocabulary acquisition by examining the development of lexical knowledge in both classroom and study abroad contexts. Taking Ife, Vives Boix, and Meara's (2000) study as a starting point, this study attempts to determine whether development in both levels of vocabulary acquisition also takes place in classroom settings. The results of this study suggest that classroom instruction does not foster lexicon development neither in size nor in depth of vocabulary knowledge. In relation to this deeper level of lexical knowledge, there is evidence that indicates that analytic and paradigmatic associations are more likely to be acquired in classroom contexts than syntagmatic ones. In contrast, study abroad students experience an increase in both levels, improving at the breadth level to a greater extent than at the associative one. The findings reported in this paper suggest that deeper level of vocabulary knowledge is more likely to be acquired in study abroad contexts since classroom instruction does not seem to offer the appropriate elements to trigger its development. (Contains 3 figures and 6 tables.)