In jurisdictions permitting prisoner smoking, rates are high (c75%), with smoking embedded in prison culture, leading to secondhand smoke exposures among staff and prisoners and challenges for smoking cessation. Momentum is building to ban smoking in prisons, but research on staff and prisoner views is lacking. We address this gap, providing evidence on staff and prisoner views throughout all Scottish prisons. Data were collected prior to the announcement of a (November 2018) prison smoking ban throughout Scotland. Mixed methods were used: surveys of staff (online, N = 1271, ~27%) and prisoners (questionnaire, N = 2512, ~34%); 17 focus groups and two paired interviews with staff in 14 prisons. Staff were more positive than prisoners about bans and increased smoking restrictions, although prisoner views were more favorable should e-cigarettes be permitted. Nonsmokers were more positive than smokers. Whilst 74% staff and 22% prisoners agreed bans were a good idea, both groups acknowledged implementation and enforcement challenges. Staff views were influenced by beliefs about: acceptability of the policy in principle and whether/how bans could be achieved. Although some voiced doubts about smoke-free policies, staff likened a ban to other operational challenges. Staff raised concerns around needs for appropriate measures, resources and support, adequate lead-in time, and effective communication prior to a ban. We recommend that regular and open opportunities for dialogue within and between different stakeholder groups are created when preparing for prison smoking bans and that specific measures to address staff and prisoner concerns are incorporated into plans to create and maintain smoke-free environments. To our knowledge, this study is the first to research staff and prisoner views across a whole prison system prior to implementation of smoke-free policies. The results highlight potential challenges and suggest measures, which might help to maximize the success of bans. Our results are relevant for prison service managers responsible for the forthcoming introduction of a ban in Scottish prisons (November 2018) and for other prison systems and comparable institutions planning smoke-free initiatives. Given that prison smoking bans may be contentious, we recommend creating regular and open opportunities for dialogue between stakeholders when preparing for and maintaining smoke-free environments.