With economic globalisation making second language (L2) learning inevitable throughout the world, understanding what factors facilitate success is a socioeconomic necessity. This paper examined the role of social factors, those related to ethnic group affiliation (EGA), in the development of L2 proficiency. Although numerous studies have documented an intimate relationship between language and EGA, few have examined whether and how this relationship shapes L2 learning. The participants were 59 adult French-English bilinguals from Quebec who read an English text and completed a questionnaire assessing their EGA, including pride, loyalty and support for their ethnic group and its language. Results revealed a significant, albeit complex, association between EGA and L2 proficiency. Basic feelings of pride and loyalty towards the ethnic group had no associations with L2 proficiency. Strong support for the group's sociopolitical aspirations were associated with low L2 proficiency. In turn, strong ethnic group identification, coupled with a positive orientation towards the L2 group, was associated with high L2 proficiency. These EGA effects were found to be mediated by amount of L2 use, revealing a plausible link sustaining the relationship between EGA and L2 learning success.