BackgroundEvidence-based interventions exist for common mental health problems. However, many people are unable to access effective care because it is not available to them or because interactions with caregivers do not address their needs. Current policy initiatives focus on supply-side factors, with less consideration of demand.Aim and objectivesOur aim was to increase equity of access to high-quality primary mental health care for underserved groups. Our objectives were to clarify the mental health needs of people from underserved groups; identify relevant evidence-based services and barriers to, and facilitators of, access to such services; develop and evaluate interventions that are acceptable to underserved groups; establish effective dissemination strategies; and begin to integrate effective and acceptable interventions into primary care.Methods and resultsExamination of evidence from seven sources brought forward a better understanding of dimensions of access, including how people from underserved groups formulate (mental) health problems and the factors limiting access to existing psychosocial interventions. This informed a multifaceted model with three elements to improve access: community engagement, primary care quality and tailored psychosocial interventions. Using a quasi-experimental design with a no-intervention comparator for each element, we tested the model in four disadvantaged localities, focusing on older people and minority ethnic populations. Community engagement involved information gathering, community champions and focus groups, and a community working group. There was strong engagement with third-sector organisations and variable engagement with health practitioners and commissioners. Outputs included innovative ways to improve health literacy. With regard to primary care, we offered an interactive training package to 8 of 16 practices, including knowledge transfer, systems review and active linking, and seven agreed to participate. Ethnographic observation identified complexity in the role of receptionists in negotiating access. Engagement was facilitated by prior knowledge, the presence of a practice champion and a sense of coproduction of the training. We developed a culturally sensitive well-being intervention with individual, group and signposting elements and tested its feasibility and acceptability for ethnic minority and older people in an exploratory randomised trial. We recruited 57 patients (57% of target) with high levels of unmet need, mainly through general practitioners (GPs). Although recruitment was problematic, qualitative data suggested that patients found the content and delivery of the intervention acceptable. Quantitative analysis suggested that patients in groups receiving the well-being intervention improved compared with the group receiving usual care. The combined effects of the model included enhanced awareness of the psychosocial intervention among community organisations and increased referral by GPs. Primary care practitioners valued community information gathering and access to the Improving Access to Mental Health in Primary Care (AMP) psychosocial intervention. We consequently initiated educational, policy and service developments, including a dedicated website.ConclusionsFurther research is needed to test the generalisability of our model. Mental health expertise exists in communities but needs to be nurtured. Primary care is one point of access to high-quality mental health care. Psychosocial interventions can be adapted to meet the needs of underserved groups. A multilevel intervention to increase access to high-quality mental health care in primary care can be greater than the sum of its parts.Study registrationCurrent Controlled Trials ISRCTN68572159.FundingThe National Institute for Health Research Programme Grants for Applied Research programme.