This article explores the degree of second language (L2) use across four communicative domains in 149 highly educated L2-proficient sequential Polish-English bilinguals resident in the UK. The domains under investigation cover: work, household, interest group, and peer group. Work and interest group count as public domains, while household and peer group count as private domains. The independent variables cover acculturation level, social network profile, predicted future domicile, and length of residence. The instruments cover an online questionnaire and semi-structured interviews. The results display that bilinguals who acculturate to a higher level employ the L2 more often, even in private domains. The findings also propose that bilinguals who operate in majority L2-speaking social networks, employ the L2 more often during informal conversations with other L1-speakers at work.