When looking at learning processes from an interactionist perspective, interaction between individuals is seen as central for learning. In order to understand and describe these interactions and therefore the learning processes, a method was developed in mathematics education grounded in the theory of Symbolic Interactionism and Ethnomethodology—the Interactional Analysis. In this chapter, at first the underlying theory for the Interactional Analysis is presented, before the steps of the method are explained, giving an example for each step. Findings of research using this method have been widely published, however, the method has not been described in depth in English yet. Therefore, this chapter makes a valuable contribution for enabling this method to be more accessible for an international research community, as well as helping international researchers understand the findings produced by using this method more clearly.