Background: Randomized controlled trials (RCTs) conducted in the routine care setting provide the opportunity to better understand the effectiveness of new medicines but can present recruitment difficulties. An improved understanding of the challenges/opportunities for patient and healthcare professional (HCP) engagement in clinical research is needed to enhance participation and trial experience. In this study, we explored patient and HCP drivers for, and experiences of, participation in the Salford Lung Studies (SLS), and their views on future trial participation and the overall value of such trials. Methods: This was a qualitative study set in Salford, UK, comprising patient telephone interviews (N = 10) and HCP advisory boards (one with general practitioners [GPs], one with practice managers [PMs]); all individuals had participated in the SLS. Semi-structured telephone interviews were recorded, transcribed and analysed thematically. Advisory board meetings were analysed based on transcriptions of audio recordings and field notes. Results: For patients, key positive aspects of the SLS were the ease/convenience of study assessments and excellent relationships with study nurses. GPs and PMs considered the SLS to be well-organized and highlighted the value of research nurse support; they also described minor challenges relating to trial systems, initial financial strain on practices and staff turnover. All participants indicated that they were very likely to participate in future trials, citing a design closely aligned with routine care practice as essential. Several strategies to encourage trial participation were suggested, such as clearly communicating benefits to patients and ensuring flexible study assessments. Conclusions: Patients and HCPs had positive experiences of the SLS. The study design, closely aligned with routine care, was considered important to their high likelihood of participating in future trials. The experiences of patients and HCPs in the SLS provide valuable insights that will help inform future best practice in the design and conduct of future real-world effectiveness RCTs in primary care. The detailed first-hand experiences of HCPs will be of significant value to others considering engaging in clinical research and participating in effectiveness RCTs.