The growing emphasis on teachers as "reflective" and "expert practitioners" has led to a noticeable increase in action research involving a wide range of educational practitioners as well as professionals from the academic community. In the light of the complex demands frequently faced by action researchers, this article examines the ethical considerations involved in conducting a collaborative action research project which is concerned with children's experiences of transition from Key Stage 2 to Key Stage 3. By exploring a range of theoretical and practical perspectives the discussion focuses on the problematic issue of "informed consent". The article argues that, as a result of having to comply with the regulations imposed by institutional ethics committees, educational researchers, particularly when working with children, are often restricted in exercising the moral autonomy and professional discretion required to negotiate the complex, potentially conflicting imperatives confronting them.