Aims and Objectives/Purpose/Research Questions: Previous studies have investigated if quantity of target language (TL) use predicts second language (L2) learning. The aim of this study is to understand what kind of TL use promotes host language proficiency among adults in the context of migration, operationalized as productive collocation knowledge. Design/Methodology/Approach: The study takes a cross-sectional quantitative approach to explore what clusters of TL activities predict language proficiency among 63 first language (L1) French L2 Swedish long-term residents in Sweden. Data and Analysis: Data were collected within a larger project. Productive collocation knowledge was assessed by a collocation test and participants’ TL use through the Language Engagement Questionnaire. We conducted a factor analysis to identify patterns of TL use. We then used structural equation modeling to investigate the relationship between TL use and productive collocation knowledge. Findings/Conclusions: Two factors emerged from the factor analysis: “Everyday Interactive Target Language Use” and “Non-interactive Target Language Use.” Only the former was related to productive collocation knowledge as evidenced by the structural equation modeling. “Everyday Interactive Target Language Use” included using the TL at the workplace, in conversations and service encounters, through text messages and emails, participating in online social network platforms, and browsing the internet. Originality: The study explores what specific kind of TL use promotes second language proficiency among adults in a migration context. This is a topic that has not received much attention in previous research. Significance/Implications: By showing that proficient L2 users engage daily with the TL through, for example, social interactions and language use at work, the study points toward the importance of a certain level of socio-economic as well as socio-cultural integration for efficient second language learning among adults in a migration context.