Introduction: Reflection is established as important in coaching and coach development, however, no research has developed an illustrative device depicting an understanding of reflection in coaching. Instead, the concept remains poorly defined, understood, practiced and supported by coaches and coach developers. The purpose of this research was to therefore produce a device to support coaches' thinking -- their reflective practice. Methods: Data were collected over a two-year period during a high-performance coach education programme delivered by a National Sports Organisation. Using an ethnographic framework, methods included participant observation of eight three-day coach education workshops, and interviews conducted at the start and end of the programme with high-performance coaches (n = 11) and coach developers (n = 12). Findings and Analysis: Based on the principles of grounded theory, analysis led to the production of a heuristic device that captures an understanding "of" reflection across two axes: types of thinking and reflection content. Conclusion: On positioning the coaches' reflective practice data within the heuristic, opportunities for assessment and intervention to develop reflection in high-performance coach education are presented and discussed.