<p>The study presented here analysed practices of non-formal adult education for sustainable development (AESD) in Slovenia. It employed mixed methods and an explanatory sequential research design. The study also examined and compared the <i>instrumental</i> and <i>emancipatory</i> approaches to education for sustainable development: the former focuses primarily on changes in individuals’ behaviours, while the latter concentrates on changes in their ways of thinking. The results show that in the practice of non-formal AESD in Slovenia, the two approaches are intertwined, with a moderate prevalence of the instrumental one. The instrumental AESD practices identified by this study mostly involve producing environmentally friendly products, reducing waste, promoting sustainable food and fashion, improving fire safety, and supporting employment. The emancipatory AESD practices were mainly identified in connection with global issues and their local implications, the social causes of environmental crises, connections between individual and societal transformations, critical reflections on the United Nations Sustainable Development Goals (SDGs), and fostering active citizenship and collective action. The two approaches were also found to influence teaching methods. Teaching practices associated with the instrumental approach typically focus on developing specific skills or achieving individual change, while those associated with the emancipatory approach tend to be participatory and tailored to each group of learners. Slovenian non-formal AESD tends to be learner-centred, with learning topics personalised to the needs and interests of learners. The most common topics are the natural environment and the human relationship to it, sustainable lifestyles, the SDGs, and climate change. The article concludes with recommendations for the policy and practice of non-formal AESD in Slovenia.</p>