This chapter examines benefits and pitfalls inherent in studying teaching and learning from the inside where the teacher is also the principal investigator of the research. The first section describes a first-person account of a trajectory using inquiry as a means of practice and using practice as a medium for research. Then, three cases of researcher-teachers' work are examined. All three focus on mathematics teaching and learning but differ in question, design, and what is afforded by the first-person perspective. It concludes with issues crucial to the ongoing development of this approach to the study of teaching and learning from the inside. (KHR)