The following Ph.D. thesis describes a research project, which aimed to explore the potential of environmental citizen science to contribute to more adaptive surface water governance in Luxembourg and beyond. Citizen science projects are research projects, which are marked by the active engagement of members of the public. Adaptive governance refers to a type of governance, which is based on the engagement of diverse types of knowledge, perspectives, and stakeholders, and on building adaptive capacity in the face of unforeseen change and coordination across levels and scales. The research contributes to the conceptual development of citizen science in the context of adaptive governance and provides an example of a co-design process with a focus on building a citizen science tool for the exploration of social-ecological systems. In addition, the thesis contributes to practical development by identifying a set of opportunities for change of current data collection and meaning-making towards more adaptive surface water governance in Luxembourg and by making first experiences with surface water citizen science in Luxembourg, while engaging multiple place-based, regional, and national partners. Towards the above-mentioned goal, the research project, first, examined the current data collection programmes and meaning-making approaches for the governance of surface water bodies in Luxembourg. Prevailing practices are discussed based on key criteria for adaptive governance based on relevant academic literature. The research project, then, examined different approaches to environmental citizen science as alternative and complementary data collection programmes and meaning-making approaches in view of their potential to contribute to more adaptive surface water governance.The research project set out to do so by taking a transdisciplinary sustainability science research approach. The methodology encompassed (1) semi-structured qualitative interviews with specialists in the water domain and documentary review to gain ...