In 2011 we, a group of English-as-a-foreign-language teachers at a secondary school in Argentina, decided to investigate our teaching practices through collaborative action research so as to improve our students' learning opportunities and thus revitalise English-language teaching in our context. We implemented and evaluated the integration of content and language learning in our classrooms through the development of our own materials. The experience revealed a growth in professional development and how our motivation and autonomy influenced our students' motivation and language development. In our attempt to disseminate our experience as a group, this report particularly focuses on the evaluation facets of our collaborative action research project so as to encourage other teachers and teacher-researchers to adopt collaborative action research to improve their own practices. (Contains 1 figure.)