Sustainability marketing research on collective consumption practices has often examined on-site actions, leaving aside online activity within brand communities. This study focuses on the online practices of communities to explain on-site sustainable practices. Online communities, which address global sustainability issues in the market, have been considered platforms for ethical consumerism for some time, yet we lack an understanding of how consumer discourse translates into practice. The research adds to the literature on online community practices by grounding it in on-site practices. The notion of community practices, which are guiding participants to make adjustments towards sustainable practices, holds potential for transformations towards sustainability. The practical implications of the research are laid out in the concluding section.