Clinical supervision is essential in developing and supporting the helping professions and is critical for delivering ethical, safe, and effective human services. Clinical supervision is widely acknowledged as a distinct professional activity, with numerous professions developing definitions of supervisor competencies for effective supervision delivery. The increased focus on competency and capability frameworks for the supervising disciplines has highlighted the critical need for accessible, relevant, and valid means of measuring clinical supervisors’ efficacy. While there have been many advances in this field, a noticeable gap in the availability of agile, reliable evaluation tools that provide multiple reflective lenses, are valid for use across diverse workforces, benchmark core competencies, and are freely accessible, has remained. Initiated by a multidisciplinary team, the Generic Supervision Assessment Tools (GSAT) is designed to fill this gap. The GSAT assesses the core supervisor competencies that are fundamental for the delivery of effective clinical supervision, regardless of profession or practice setting. Consisting of three tools (GSAT-SR Supervisor, GSAT-SE Supervise and GSAT-A Assessor) the GSAT is designed to capture and triangulate multiple reflective lenses to enhance reflective feedback. Through this body of research, I developed, piloted, and psychometrically validated the GSAT, to test its efficacy across a broad cross section of supervising professions. Four sequential studies informed the final validation of the suite of GSAT tools.