This Language Teacher Cognition (LTC) study primarily explores language teachers' beliefs and practices about a common Instructed Second Language Acquisition (ISLA) construct: Grammar Teaching (GT). This study also aims to investigate to what extent teacher beliefs and practices compromise with each other and cognitive and contextual factors behind their cognition. The data were collected through interviews, observations, and stimulated recall with the teachers. The findings after a cross-case analysis revealed that course book-based beliefs, experience-based beliefs, lack of theoretical knowledge and inclination for communicative activities influence what teachers believe about GT. There are both congruent and incongruent relationships between beliefs and practices varying from one teacher to another due to the effect of experiential knowledge, unconscious decisions, and some contextual factors. The findings can contribute to the integration of LTC into ISLA studies, and to LTC framework by exploring the effects of many variables on teachers' decision-making processes.