Both the sustainability discourse and the debate on citizen science are strongly focused on the natural and technical sciences. Yet, numerous participatory research activities can be identified in the social sciences and humanities that address sustainability issues of various kinds. These have hardly been studied so far, and their contribution to addressing sustainability challenges is poorly known. The study investigates which sustainability topics are taken up by citizen science in the humanities and social sciences, which factors influence the choice of topics, and its implications. For this purpose, the concept of Citizen Social Science (CSS) is taken up and sustainability is operationalized via the Sustainable Development Goals (SDG) and its specific Targets. Based on a collection of CSS activities in Germany, the addressed sustainability topics are identified accordingly. It is then analyzed how these patterns depend on the main characteristics of CSS projects. The findings indicate a focus on three SDGs related to education, sustainable cities and partnerships for the Goals, while at the same time the project consortia are very heterogeneous. CSS shows particular strengths here through its multi-stakeholder approach. Going forward, the linkage of Citizen Science to the SDGs needs to be further formalized so that its transformative effects can be incorporated into SDG monitoring and the scientific institutions need additional incentives to participate in CSS.