BACKGROUND: Social determinants of health (SDOH) critically impact on population and individual health outcomes and underpin health inequalities, yet information on individual-level social risk are not collected routinely in healthcare settings. AIM: The aims of this study are to investigate the feasibility of SDOH screening in primary care, validate a proposed screening tool, explore acceptability of screening, and estimate the burden of social need in the study population. DESIGN AND SETTING: This explanatory sequential mixed-methods study is conducted in UK general practice. METHOD: In Work Package (WP) 1, we will compare methods for collecting social determinants of health (SDOH) data using a screening tool: text message, post with online option, telephone, and opportunistic collection in consultations. Linked medical records will describe characteristics of patients with social needs and estimate prevalence. We will also assess reliability and validity of the screening tool.In WP 2, patient interviews will explore screening acceptability, including barriers and facilitators. Focus groups and interviews with GP practice staff and community healthcare professionals will examine views on screening and its integration into routine workflows. Data will be analysed using Braun and Clarke's thematic analysis. CONCLUSION: Identifying those with unmet social needs will potentially: support clinicians to provide better personalised care, improving health outcomes; provide better information on local populations; allow for targeted support for those with unmet needs; help develop local services; and inform public health policies to reduce health inequalities. Results from this study will inform a randomised controlled trial in a larger programme of work.