BackgroundSouth Asian children are more likely than others to suffer from their asthma and be admitted to hospital. The UK Public Health Outcomes Framework focuses on partnership across locally led systems to plan and deliver health-care services in the context of broader social determinants of health. The Management and Interventions for Asthma (MIA) project aimed to embody localism by using a collaborative, participatory model to develop an intervention designed to improve asthma management in South Asian children. MethodsThe project was multi-phase, iterative, and participatory, underpinned by the socio-ecological model of health, recognising the importance of issues arising from the individual, family, wider community, and organisational and environmental contexts of family health. Building on this model, the project worked collaboratively with linguistically and culturally competent community facilitators (CFs), to engage and develop a partnership between South Asian community members, parents and children living with asthma, health-care professionals (HCPs), and researchers. The study had four phases. Phase 1 consisted of an evidence review of barriers and facilitators to asthma management in South Asian children. Phase 2 explored lay understandings of asthma in South Asian children using focus groups (n=67) with members of South Asian communities (Indian, Pakistani, Bangladeshi) recruited by trained CFs. Phase 3 explored experiences of asthma management via semi-structured interviews with South Asian and White British parents and children (n=82 participants) recruited from the NHS and by CFs and included semi-structured interviews with HCPs (n=37). Focus groups and interviews were done in the preferred language of the participants. Focus group facilitators and interviewers were trained and supervised to reduce bias. Data were analysed with principles of interpretive thematic analysis facilitated by NVivo. Interviews with a comparison sample of White British parents and children (n=31) identified aspects of asthma management that could be addressed by generic interventions and those needing a tailored approach. Data from phases 1–3 were combined with thematic analysis to identify 11 key themes that needed to be addressed to optimise asthma management. In phase 4, an intervention planning framework was developed, with a novel modified intervention mapping approach incorporating psychological theory. Collaborative workshops, including parents, children, academics, and HCPs, were held to integrate data, develop an asthma intervention planning framework, and prioritise one aspect of asthma management to be used as an exemplar for the tailored intervention programme. FindingsThe 11 key themes were: being able to talk to doctors and nurses, being able to use services, community awareness of asthma, getting a diagnosis, having suitable information on asthma, medicines for asthma, school and my child's asthma, services available for asthma, quality of care, understanding asthma, and what to do day to day. Parents chose getting a diagnosis as a priority and a multifaceted programme, ACT (awareness, context, training) on asthma, was developed as an exemplar intervention, consisting of community awareness, education and training, clinical support, and a central advice centre, coordinated by a central team. Recruitment targets were exceeded and participants gave positive feedback. InterpretationKey issues in optimum asthma management in children arise at the patient, provider, and health-care system levels and interventions must address all these levels. Minority ethnic communities can be successfully engaged in collaborative intervention development with a community focused and culturally sensitive methodology. FundingNIHR Health Services and Delivery Research (HS&DR) Programme (09/2001/19). Views and opinions expressed those of the authors and do not necessarily reflect those of the HS&DR Programme, the NIHR, the NHS, or the Department of Health.