This article explores theoretical and methodological issues associated with task-based interviews conducted with pairs of children. We explore different approaches to interviews from sociological, psychological and subject-based perspectives. Our interviews, concerning mathematical questions and carried out with pairs of 10 and 11-year-olds, are drawn on and we conclude that the consensus and conflict identified as being associated with paired interviews in social science paradigms are also relevant to task-based interviews, but take different forms. Children interviewed in pairs about tasks they have previously completed sometimes show cognitive conflict related to mathematics, but sometimes the conflict has social bases. Children interviewed in pairs whilst they work on tasks often search for consensus, which can take the form of co-construction of knowledge. (Contains 2 figures and 2 tables.)