Background: Whilst the benefits of physical activity for health and wellbeing are recognised, population levels of activity remain low. Significant inequalities exist, with socioeconomically disadvantaged populations being less physically active and less likely to participate in community events. We investigated the perceived benefits from participation in a weekly running/walking event by those living in the most socioeconomically deprived areas and doing the least physical activity.Methods: A cross-sectional online survey was emailed to 2,318,135 parkrun participants in the UK. Demographic and self-reported data was collected on life satisfaction, happiness, health status, physical activity, motives, and the perceived benefits of parkrun. Motivation, health status and benefits were compared for groups defined by level of physical activity at parkrun registration and residential Index of Multiple Deprivation.Results: 60,000 completed surveys were received (2.7% of those contacted). Respondents were more recently registered with parkrun (3.1 v. 3.5 years) and had a higher frequency of participation than non-respondents (14.5 v. 3.7 parkruns per year). Those who were inactive at registration and from socioeconomically deprived areas reported lower happiness, lower life satisfaction and poorer health than the full sample. They were more likely to want to improve their physical health, rather than get fit or lose weight. Of those reporting less than one bout of activity a week at registration, 88% (87% in the most socioeconomically deprived areas) increased their physical activity level and 52% (65% in the most socioeconomically deprived areas) reported improvements to overall health behaviours. Previously inactive respondents from the most socioeconomically deprived areas reported greater improvements to fitness (93% v. 89%), physical health (90% v. 85%), happiness (83% v. 79%) and mental health (76% v. 69%).Conclusion: The least active respondents from the most socioeconomically deprived areas reported changes to their activity levels and benefits to their health and wellbeing since participating in parkrun. Whilst the challenge of identifying how community initiatives like parkrun can better engage with the least active and most socioeconomically deprived remains, if this can be achieved, then such interventions can have a critical public health role in addressing inequalities in benefits associated with recreational physical activity.