In this article we argue that conceptual competence should be seen as a component of second language (L2) communicative competence. Abstract concepts are highly expressed by means of metaphors, metonymies, idioms and other types of figurative language. In literature it is suggested that knowledge and appropriate use of these lexical segments are closely related to L2 mastery and therefore conceptual instruction is expected to facilitate L2 learning. To test the relationship between conceptual and L2 competence we conducted an experiment in which Modern Greek learners were encouraged to express their views on the concept of happiness. The results showed their weak performance in conveying their ideas in a coherent and acceptable manner.