Over the last three decades research in beliefs, and affect more generally, has developed into a significant field of study. It attempts to make sense of teachers’ and students’ understandings of mathematics, of its teaching and learning, and of themselves as doers, teachers, and learners of mathematics and of how these understandings relate to classroom practice. Studies of these issues have been published widely and in the most prestigious journals and book series. However, belief research is still confronted with significant conceptual and methodological problems. I suggest that this is at least in part due to the dominant conceptualization of individual functioning in belief research, one that is based on acquisitionism with its emphasis on human action as an enactment of previously reified mental entities. In the present chapter I build on social practice theory and symbolic interactionism to rephrase key issues of belief research, especially that of the relationship between beliefs and practice, in more participatory terms. The suggestion is to shift the focus from beliefs to the pre-reified processes that are said to give rise to them. This leads to more dynamic understandings of learning and lives in mathematics classrooms and serves to overcome some of the conceptual and methodological problems of the field.