The study investigates how psychological and social factors relate to productive collocation knowledge in late L2 learners of Swedish (French L1) (N = 59). The individual factors are language aptitude (measured through the LLAMA aptitude test), reported language use, social networks, acculturation, and personality. Multiple linear regression analysis showed that positive effects were found for LLAMA D (phonetic memory), LLAMA E (sound-symbol correspondence), reported language use, and length of residence (LOR). Furthermore, a negative effect was found for the personality variable Open-mindedness. These variables explained 63% (adjusted R²) of the variance, which represents large effects compared to other studies on individual factors. In sum, the findings confirm earlier results on the importance of language aptitude and language use for productive collocation knowledge. They also add evidence of the importance of personality and LOR. In sum, cognitive and social factors combine to explain different outcomes in adult L2 acquisition.