Ensuring that practitioners are competent in the therapies they deliver is important for training, therapeutic outcomes and ethical practice. The development of the Systemic Practice Scale (SPS) is reported - a measure to assess the competence of novice systemic practitioners trialed by Children and Young Person’s Improving Access to Psychological Therapies (CYP-IAPT) training courses. Initial reliability assessment of the SPS with twenty-eight supervisors of systemic practice evaluating students’ competence using an online recording of a family therapy session is detailed. The SPS was found to be a reliable measure of systemic competence across training settings. Rating variability was noted, with training and benchmarking to improve rating consistency recommended. Further research using the SPS to further establish the reliability and validity of the scale is required.