This paper describes the development of a scale for measuring systemic supervision which is called the Systemic Supervision Rating Scale (the 3D-SSRS). This scale was developed through a thematic synthesis of the systemic supervision literature, which included 137 papers on the subject. The scale was then subjected to a face validity investigation via a series of qualitative focus groups. These groups included both supervisors of supervision and students on an AFT Accredited Supervision training. Focus groups were held at the beginning and at the end of the course to understand how useful the 3D-SSRS was to supervision practice. The 3D-SSRS uses a seven-point scale to rate supervision practice and prioritises qualitative comments in 11 dimensions, including the supervisory relationship, context of supervision, developmental stage of supervisee, development of systemic skills and thinking, and attention to power and difference. Practitioner points: Systemic supervision draws on knowledges and skills unique to systemic practice within specific contexts. A new Systemic Supervision Rating Scale (the 3D-SSRS) has been developed for use in clinical and training contexts of supervision. Initial investigations into the usefulness and face validity of the scale find it able to capture many of the unique aspects of systemic supervisory practice. More research is needed into what makes for effective live supervision, perhaps unique to systemic supervisory practice, and supervision provided to groups.