Abstract Background Across Europe, smoking prevalence is concentrating in underserved communities with high levels of deprivation. And yet, there is little research on how stop smoking services (SSS) can engage these communities. This study presents the findings of a 12-month collaboration involving an external public health research team and staff of an English SSS. Staff worked with community partners (e.g., schools) to raise awareness of the service, which included a newly introduced e-cigarette offer. Methods A complex intervention model was developed and refined through 6 facilitated co-inquiry sessions involving 13 SSS staff. Staff also completed 32 reflection forms on outreach events and rapid ethnography was conducted, by the research team, to evaluate staff’s working assumptions. This included 8 observations of outreach events and interviews with 10 SSS staff and 8 community members, from the service target groups. Data were organised into themes. Findings The model presents a picture of stop smoking outreach as challenging, unpredictable and resource intensive yet often having great impact. The themes enrich this to highlight 1) the appreciation for yet unpredictability of outreach referrals for people disconnected from health services; 2) the importance of staff adopting a person-centred approach; 3) the challenges and opportunities presented by e-cigarettes; and 4) the role of strategic community partnerships in optimising staff time on outreach. Conclusions Stop smoking outreach can generate considerable interest in SSS, particularly when delivered in combination with an e-cigarette offer. Future research should explore the economic and social return on investment in community outreach: while time consuming, referrals generated proactively may become more important for SSS as smoking concentrates in underserved communities. Key messages • Stop smoking outreach is an effective way to raise awareness and generate referrals but must be done non-judgementally and via effective community partnerships. • Staff’s careful discussion of an e-cigarette offer can change the perception of SSS without contributing to recreational normalization.