Conceived in 1950, the Colombo Plan for Co-operative Development in South and Southeast Asia was a unique experiment in foreign relations.Meeting annually across what we now know as the 'Indo-Pacific', talented administrators facilitated foreign aid provision, and promoted development fuelled state-making, internationalism and experimental regionalism across postwar Asia.David Lowe argues that this new setting and dynamic international cast created an unusually productive diplomatic environment of development internationalism.The Colombo Plan did not escape power politics or Cold War divisions.However, it did run according to its own rhythm, and, unlike other experiments, it endured, continuing today in much reduced form.