For its 2013/2014 independent evaluation cycle, GIZ’s Monitoring and Evaluation unit commissioned portfolio evaluations with a focus on rural development. Among them was the ex post evaluation of “the German contribution to the sustainable management of the Lower Mekong Basin through the support of the Mekong River Commission,” assigned to Humboldt University’s Centre for Rural Development (SLE). Seven participants of SLE’s 51st postgraduate course and two team leaders evaluated two development measures: “Sustainable watershed management in the Lower Mekong Basin” (GTZ) and “Potentials of rural areas in Mekong countries” (InWEnt). The projects aimed at improving watershed management, building capacity, and increasing political dialogue among Cambodia, Laos, Thailand, and Vietnam. The team used OECD-DAC and GIZ criteria, conducted a two-month preparatory phase, reviewed 200 documents, and collected qualitative and some quantitative data during three months of fieldwork. Methodologies included interviews, focus groups, timelines, and the ‘most significant development’ tool. Despite data access challenges, the team’s extended on-site presence enabled broad data collection. Results show that the GTZ project partly achieved its objectives: action plans were developed, regional dialogues improved, and local improvements in water quality and reduced deforestation were observed, but harmonisation and replication were limited. The InWEnt project trained many but lacked institutional anchoring; however, local partnerships thrived, and participation increased. Recommendations were provided for institutional learning. The team highlighted the importance of cultural sensitivity, clear evaluation objectives, and precise indicators for future evaluations.