The aim of this study is to evaluate the feasibility and acceptability of a new community-based programme designed to tackle loneliness for young and working-age adults. The programme focuses on encouraging social interactions and connections through offering community initiatives and activities, online spaces for interaction, and free or low-cost social events for young adults. Further aims of this study are to determine the cost-effectiveness of the programme.

Loneliness is associated with adverse mental and physical health outcomes. Most interventions are aimed at older adults even though young adults, including those of working-age, have been identified as being at-risk for persistent loneliness. This study aims to formatively evaluate the feasibility and acceptability of a community-based social interaction intervention. Therefore, the main objectives of this study are to:

1. Assess the feasibility and acceptability of the community-based intervention.
2. To determine the costs and effects related to the community-based intervention using quantitative feasibility study data and qualitative interviews with study participants.

In this mixed-methods two-arm randomised feasibility study with qualitative evaluation, participants will be randomly allocated to the community-based intervention over 12 weeks or to the wait-list control group. The intervention consists of weekly community social activities with the aim of reducing feelings of loneliness. Participants in the wait-list control group can continue any standard care or support they were receiving e.g. use of GP or mental health services. For both groups, online self-report assessments will take place at baseline (time 0, t0), 12-week follow-up (end of the intervention period; time 1, t1) and 6-weeks post intervention (18-weeks after baseline, time 2, t2). For the intervention group, an additional qualitative interview will be taken at the final timepoint (time 3, t3; 6 weeks post-intervention).

Inclusion Criteria:

• Age 20-40
• Reside in London
• Reports that they are some of the time or often lonely in response to a single questionnaire item ("How often do you feel lonely?)
• No prior interaction with the community-based intervention we are investigating
• Able to communicate in English sufficiently well to engage in qualitative interviews and complete the outcome measures and questionnaires.
• Available and willing to participate in the study for 18 weeks

Exclusion Criteria:

• Age < 20 or age >40.
• Resides outside of London.
• Does not report frequent levels of loneliness ("hardly ever or never" in response to single questionnaire item).
• Previously attended any event or is an existing member of the community-based programme that is forming the intervention arm.
• Unable to communicate even with communication support.
• Planned unavailability for >3 weeks during intervention and follow up periods.
• Participating in another research project related to loneliness.
• Reports current severe unstable health problems (mental or physical) or is deemed overburdened with respect to participating in research.

Participants' anonymised data may be shared with other research scientists for the purposes of research and knowledge.

Fully anonymised and non-identifiable study data will be available 6 months following the project's end, and will be kept by the PI for at least 10 years in the approved long-term repository in the UK.

Participants' anonymised data may be shared with other research scientists for the purposes of research and knowledge. This data will not be able to be traced back to participants. The datasets will be available upon request from Professor Jennifer Lau, who is the lead researcher.