BackgroundOutdoor smoke-free policies (SFPs) at sports clubs can contribute to protecting people from second-hand smoke (SHS). However, in absence of national legislation, it is uncertain whether and how sports clubs decide to adopt an SFP. The aim of this study was to explore the decision-making process at sports clubs in relation to the adoption of an outdoor SFP.MethodsSemi-structured interviews were held with key stakeholders at 20 Dutch sports clubs (in field hockey, football, tennis, or korfball) with an outdoor SFP. Thematic analysis was applied, and themes were defined in line with the four streams of the Garbage Can Model (GCM).ResultsWe identified four motivating factors for sports clubs to start the decision-making process: 1) SHS as a problem, 2) intolerance of smoking behavior, 3) advantages of an outdoor SFP, and 4) external pressure to become smoke-free. The decision-making process involved a variety of participants, but the board, influential club members, and smokers usually played major roles. Decisions were discussed during both formal and informal choice opportunities, but only made during formal choice opportunities. With regard to solutions, sports clubs adopted a partial or total outdoor SFP. In addition, sports clubs followed different strategies with regard to the decision-making process, which we classified along two dimensions: 1) autocratic vs. democratic and 2) fast vs. slow.ConclusionA number of factors motivated sports clubs to start the decision-making process. These factors were mainly linked to a strong non-smoking norm. Decision-making involved different participants, with a key role for the board, influential club members, and smokers. Governments and other external organizations may contribute to SFP adoption at sports clubs in several ways. They may advise clubs on strategies of decision-making and how to involve smokers in this process.