With heightened equity pursuits in 21st century schools and the key role of assessment in teachers' concerns with educational equity, scholars have recently attempted to empirically investigate teachers' conceptions of fairness in classroom assessment. This study contributes to this growing literature and draws on interview data from 27 experienced high school teachers to further appreciate the factors that propel teachers' fairness conceptions. The results indicate that the teachers' conceptions of fairness in classroom assessment were influenced by three themes: (a) "individual mechanisms," (b) "social mechanisms," and (c) "dialectical relationships between individual and social mechanisms." These themes underscored how teachers' individual philosophies and experiences interacted with their encounters with social conditions of society, schools, and classrooms to influence their conceptions and articulated practices of fairness in classroom assessments. The results contribute to provoke conversations around assessment fairness education during pre- and in-service programs.