This issue of the "ZERO TO THREE" journal provides a snapshot of the current state of measurement of reflective supervision within the infant-family field. In this article, the authors introduce the issue by providing a brief history of the development of reflective supervision in the field of infant mental health, with a specific focus on research regarding reflective supervision. They highlight why research on reflective supervision is vital to the field and provide an overview of current research methods. The emerging research methods and implications are discussed in more detail in the other articles in this issue.