In this article, I explain why it is important for theologians to involve children in empirical research, and why children themselves can and should be considered as ‘theologians’. Therefore, I refer to theories in childhood studies and child theology (children as active participants and subjects), and also to contemporary trends in empirical research and practical theology (views on theology and ethnography, lived religion etc.). Counter-arguments for involving children in empirical research are discussed as well. In the second step, I deal with ethical issues and discuss which aspects have to be taken into account when doing research with children.