This mixed-methods study aims to explore the patterns of teacher and their effects on teachers' lives and work. To do so, the researchers went into one international school in Thailand and requested participation from 25 foreign language (FL) teachers. All the participants completed and returned a questionnaire and participated in one-on-one interviews and observations. Calculation of the questionnaires with SPSS (version 20) demonstrated the participants' high favoritism of teachers' collegial relations. Nevertheless, the researchers' analysis of their descriptive data with open and axial coding techniques opposed the numeric data and strongly supported the existence of balkanization, individualism, and contrived collegiality among these participants. The findings of the present study challenge (FL and other subject disciplines) teachers to consider the focus and the depth of teacher cultures. More importantly, they urge teachers, school administrators, and policy makers to anticipate the growing effects of teacher cultures on teachers' sense of professionalism related to their lives and work.