Complexity is a characteristic of problem fields related to mathematics education and, in any study; the researcher has to focus on one of the problems without ignoring the others. Diversity (gender, ethnicity, social class etc.) in the subject area calls for multi- and inter-disciplinary studies and for different research methodologies. The concept of sociomathematics is developed and suggested as a name for a subject field where people, mathematics and society are combined, and for the research field where the societal context of knowing, learning and teaching mathematics is taken seriously into account. This is done through a critical dialogue with ethnomathematics.