This study examined the main sources of the participant English as a foreign language (EFL) teachers' cognitions, their classroom practices and the impact of institutional context on these practices. The participants included three Turkish EFL instructors working at English preparatory programs at university level. The data were collected through three semi-structured interviews, twelve hours of classroom observations with follow-up stimulated recall interviews, and reflective journal entries. To analyse the data, grounded theory design was used as a systematic data analysis process. The findings showed that prior language learning experiences, the pre-service education, the years spent as a novice teacher, institutional atmosphere, experienced colleagues in the past and all teaching experiences were the main sources of their cognition on language teaching and their cognitions were also the origin of their classroom practices. The learner profile, institutional factors including the organizational atmosphere, testing and curriculum policies, and the participants' improvisational teaching acts were the other factors shaping their practices. Finally, the study puts forward a language teacher cognition model, Clusters of Language Teacher Cognition, a figurative conceptualization which would guide researchers for further studies and policy-makers for designing the learning-to-teach processes of teachers.