Non-formal education projects are seen as taking a key role regarding Education for Sustainable Development; however, the conditions of participation are still scarcely explored. The objective of this study is to develop a concept helping to understand the resources, motivations, underlying values, and context of parents in the process of choosing a non-formal Education for Sustainability project in Germany for their children aged six to twelve. For this, the school choice concept of Raveaud and van Zanten, which is utilizing “resource” definitions in approximation to Bourdieu’s capital, is adapted for the non-formal sustainability education sector, by implementing the concept of environmental capital, conceptualizing the choice framework for non-formal sustainability education. Ten interviews with parents from such projects have been conducted in the summer of 2021 and analysed based on the newly developed choice framework for non-formal sustainability education. Unlike what the adapted school-choice theory suggests, the local normative framework has little impact on the choices parents make in the non-formal choice process. The results indicate that especially cultural resources within the framework of environmental capital and accumulated in the informal learning space have had a formative impact on the parents, which let them to enrol their children to participate in the sustainability education projects. In comparison to formal school choice processes, the tension between impersonal and personal values is not as tangible for parents. As projects combine expressive values like self-realisation and impersonal values like environmental awareness in their pedagogical approaches, parents are even able to satisfy both their personal and impersonal values while choosing an SE project. It is being discussed how parents can be strengthened in their role to pass on sustainability values, without creating an even greater inequality regarding environmental capital, as well as the importance of a symbiosis between EE and ESD projects to further sustainability education in Germany.