BACKGROUND: Asthma is a long-term lung condition affecting 1 in 11 children and young people in the UK. Many teenagers have well controlled asthma, but a significant number continue to experience regular symptoms and asthma attacks leading to hospitalisations. While non-adherence to medication is a factor, teenagers also face challenges like changing relationships with parents and peers, avoiding triggers like smoking, and fitting in treatment with daily life demands. Healthcare professionals (HCPs) also face difficulties in managing teenagers with asthma. A previous study, funded by Asthma + Lung UK, developed a new approach to manage teenage asthma by focusing on self-efficacy, which is how confident one feels about performing a task. Teenagers completed the Adolescent Asthma Self-Efficacy Questionnaire (AASEQ), which identified areas where they needed more support. HCPs then tailored their consultations to address these needs. This approach improved the teenagers' confidence in self-managing their asthma. Improving quality of life (QoL) is a key goal in asthma care. Therefore, the aim of this study is to determine if the self-efficacy approach improves QoL for teenagers with asthma. METHODS: Teenagers aged 12-18 years with asthma will be recruited from hospital clinics. They will be randomly assigned to one of two groups: 1. Teenager will complete the AASEQ at the start of their appointment. The HCPs will use this to focus the consultation on areas where the teenager needs support in self-managing their asthma. 2. Teenager will have their usual consultation with the HCP. Three months after the appointment, the QoL will be compared between the two groups using a standardised questionnaire. IMPACT: If the self-efficacy approach proves to be beneficial, it could help HCPs to empower teenagers to better manage their asthma and ultimately improve their quality of life.