Young people with symptoms of one or more neurodevelopmental conditions experience much higher rates of mental health problems (e.g., anxiety, depression)than their peers. The Embracing Complexity charity coalition, our non-HEI partner, has highlighted the significant barriers that neurodivergent young people face in receiving prompt recognition and support for mental health problems, but we still do not have a full picture of the drivers of these disparities. Two reasons for this knowledge gap are that most studies have focused on specific neurodevelopmental conditions (e.g., autism), even though they co-occur in most neurodivergent individuals, and on participants from White privileged backgrounds. This PhD project will seek to improve awareness of mental health problems and facilitate access to mental health support in neurodivergent young people, particularly those with co-occurring neurodevelopmental conditions and belonging to minority ethnic groups. Drawing on the frameworks of neurodiversity and intersectionality, we will investigate barriers to receiving a mental health diagnosis and support faced by neurodivergent young people, and whether co-occurring neurodevelopmental difficulties and ethnicity play a role in these health disparities. We will use a mix of quantitative, qualitative and participatory research methods, including the involvement of a research advisory group of neurodivergent young people with lived experience. First, a systematic literature review will highlight key knowledge gaps by summarising research onthe barriers to mental health diagnosis and support across types of neurodevelopmental difficulties and ethnicity.Second, we will quantify the challenges in accessing amental health diagnosis and support in the community experienced by neurodivergent young people relative to non-neurodivergent peers with comparable mental health problems, and test the impact of co-occurring neurodevelopmental difficulties and of belonging to minority groups. This will capitalise on diverse existing longitudinal cohorts with information on neurodevelopmental difficulties and mental health problems reported by parents/carers and young people alongside mental health diagnoses and support accessed in the community. Finally, surveys and focus groups with neurodivergent young people and their parents/carers will investigate their lived experiences and identify possible solutions for addressing these mental health disparities. Embracing Complexity will support all research and dissemination activities, including recruitment and involvement of diverse groups of neurodivergent young people for the new data collection and advisory group. This work will address the priorities of neurodivergent young people typically excluded from research and improve awareness of mental health needs and disparities in this population. Findings will inform training provision and guidelines for clinicians and educators working with neuro divergent young people.