Heron's six category intervention framework, delineating key intervention styles within helping relationships, was developed to guide therapeutic work but has also been applied to supervisory work. Some previous research has investigated this framework's relevance for practice but there has been no previous research analyzing its application to supervision. Following a longitudinal, naturalistic, observational case study design, this study aimed to analyze and illustrate the usefulness of the six category intervention framework as a guide for supervisory practice. Individual meetings of five supervisory dyads in an Irish transdisciplinary, brief-intervention, public youth mental health service were recorded for 6 months. A codebook applying Heron's intervention framework to supervision was developed inductively and deductively, good interrater reliability was established, and transcripts of 20 of the dyads' supervision meetings were coded and analyzed. Informative interventions were found to be most dominant, followed by supportive and prescriptive interventions. Catalytic interventions were seldom used, and confronting and cathartic interventions were rare. It is concluded that the high use of informative interventions fitted the needs of early-career supervisees and the high pace of a brief-intervention service. However, a greater balance of interventions is recommended in supervisory practice, particularly more catalytic, cathartic, and confronting interventions, in order to foster supervisee autonomy and capability. Detailed illustrations of seldom-used interventions are presented and analyzed, and opportunities for their greater use are considered. It is concluded that the six category intervention framework offers a useful guide for supervisor training and ongoing development of supervisory practice in workplace settings. Impact StatementHeron's (2001) six category intervention framework was found to be valuable for evaluating and illustrating supervisory interventions in a transdisciplinary, youth mental health service. Informative, supportive, and prescriptive interventions were predominant in the supervision of early-career practitioners within a fast-paced, brief-intervention service. This study's illustrations and analyses can help supervisors to identify opportunities for greater engagement in catalytic, cathartic, and confronting interventions, which are important in fostering supervisee autonomy and capability.