In the decades to come, global climate change poses a significant environmental, social, and economic threat. Among the various strategies that are being implemented to reduce this threat are those that focus on decreasing greenhouse gas emissions by supporting the climate-friendly behaviour of the general public. The present study is focused on Czech Greenpeace donors. These donors represent a segment of the public that, while engaged in supporting systemic policy measures in the area of climate protection, also has the potential to grow in the area of climate-friendly household behaviour. Our research is based on a sample of 504 respondents and deals with this group’s climate-relevant household behaviour. In relation to Community-Based Social Marketing, we examine the potential of Greenpeace donors to behave in a climate-friendly way, and we identify the barriers that prevent them from getting involved in a broader spectrum of climate-friendly behaviour. Our analysis is informed by several significant contemporary theories of pro-environemntal behaviour. We also highlight topic areas on which to focus when encouraging Greenpeace donors to further improve their climate-friendly behaviour.