In light of findings from research on informal foreign/second language (L2) learning, with a focus on English as a target language and using the concept of extramural English (EE), this position paper argues that learners’ engagement in EE (through activities such as watching television or films or playing digital games) constitutes an important individual difference (ID) variable that needs to be included in studies that aim to measure L2 English proficiency or development. In addition, it is suggested that if EE as an ID variable is left out in such studies in the future, the rationale for exclusion should be clearly stated. This position paper also discusses research instruments and methods used in this area of research, the benefits and drawbacks of different methods, and identifies research gaps and under-researched learner groups. Further, it is argued that in some contexts, EE has replaced classroom activities as the starting point for and foundation of learning English.
