This collaborative action research study aimed to explore if and to what extent compensation strategy instruction (CSI) can improve the communicative competence of learners of EFL who mainly use L1 in classroom speaking activities. Designed by a university professor and an EFL instructor working at a state university in Turkey, the study was conducted with B1-level learners, aged 17-18, studying at the English Language Centre of the university. The study followed an action research intervention framework. In the second cycle of the intervention process, instruction in affective strategy use was provided in response to the emerging need for dealing with learners' anxiety and stress. The findings indicate that learners can be taught how to use compensation strategies and that CSI may be useful for improving learners' communicative competence in a speaking class. However, affective factors, if not addressed, can hinder learners' effective use of compensation strategies.