Borderline personality disorder (BPD) diagnosis in adolescents is a relatively recent concept and a fast-emerging research area. Regarded by some as controversial, it is important for research to provide greater understanding of differing perspectives and their impact on the use of this diagnosis. Perspectives of 13 clinicians (therapists, psychiatrists and mental health nurses) were explored, to provide a contemporary understanding of perceptions and use of BPD diagnosis within child and adolescent mental health services in England. A particular focus was to explore dilemmas faced by clinicians and how these dilemmas were negotiated. This research took a qualitative, social constructionist approach to explore the in-depth views and experiences of each participant. Interviews were analysed using thematic analysis, to seek out patterns and commonalities across these clinical perspectives. Three overarching themes were generated: ‘Who holds the power?’, ‘Dilemmas within the multidisciplinary team (MDT)’ and ‘The weightiness of making this decision’. Professional opinions of an adolescent BPD diagnosis are influenced by dominant and less dominant mental health discourses, including the impact of power, and availability of resources within the service context. The role of meaningful collaboration with young people, clinical implications and directions for future research are discussed.