In this theoretical paper, we draw on Panopticism (Foucault, 1975/1995) to consider how an emphasis on productive beliefs for teaching and, especially, the practices of measuring, categorizing, and correcting beliefs through research and teacher education create and sustain mechanisms of power within mathematics education. We highlight examples from the existing research on mathematics teachers’ beliefs as well as data collected from a small group of teachers to describe possible distributions of power. Through the instruments that researchers create and use to measure beliefs and the beliefs that we, as educators, collectively value as productive (our Panopticon), the functioning of power becomes bigger than any one teacher, researcher, or teacher educator.