While SLA studies on the acquisition of sociolinguistic variation have primarily illuminated the impact of social and socio-biographic factors on such development, this paper is a response to the need for studies of the relationship between sociolinguistic development and other components of the learner's L2 linguistic repertoire, such as grammatical development, which is the focus of this study. With the aim of exploring the hypothesis that grammatical development is a pre-requisite to sociolinguistic development, the study presents quantitative findings which compare longitudinal development on a number of grammatical and sociolinguistic features in the case of Irish university learners of French. Findings suggest that while grammatical development may be important, it may be not enough, such that it is naturalistic exposure which provides the necessary impetus for such sociolinguistic development. Moreover, the extent of grammatical development in terms of the range of grammatical features which are productively used within the learner's linguistic repertoire is a further factor which complexifies the issue.