There is growing consensus that political factors are a key determinant of development impact. The practice of Thinking and Working Politically (TWP) is built around three interconnected principles: (i) strong political analysis, insight, and understanding; (ii) detailed appreciation of, and response to, the local context; and (iii) flexibility and adaptability in program design and implementation. The literature notes that while TWP emphasises the centrality of politics and power, technical knowledge is still important and can reinforce the political agenda, for example by increasing the confidence of smaller states or by strengthening collective understanding. Furthermore, improving the quality of domestic cooperation can be a step towards regional cooperation, and flexible engagement with the diverse range of actors that populate transboundary settings has been shown to be an effective strategy. The literature also highlights lessons learned including Transboundary cooperation can be built from the bottom up and for development partners, pre-existing bilateral partnerships may facilitate their engagement at a transboundary level, particularly on sensitive issues. Given the relatively isolated experience of TWP in transboundary settings, the evidence base for this report is also limited. The two areas where most examples were found concern regional integration and transboundary water management.