Many development initiatives make use of foreign technical assistance (TA) for implementation of programme activities. In countries with poor human resources, such as Cambodia, so-called foreign "experts" and "consultants" can be found in most central government institutions. Typically the foreign TA is contracted by donor agencies or the government itself to nominally fulfill an institutional capacity-building or support role. This research aims to look at the role of foreign TA in Cambodia and its effectiveness as an intervention for sustainable development. In particular, methods of building productive counterpart relationships, and personal workplace behavior, are analyzed from both the experts' and government's perspective in an attempt to discern fundamental characteristics that enable foreign TA to most effectively contribute to sustainable development. The study makes use of in-depth guided interviews with foreign development practitioners and their government counterparts in Cambodia's capital city, Phnom Penh. Structured e-mail questionnaires and personal experience supplement this data source. Research findings indicate that the foreign expert's role is typically vague, yet varies depending on his/her surrounding government office environment. There is consensus that experts should focus on long-term "people sustainability," rather than short-term technical sustainability. Personal qualities, advantages, and disadvantages of foreign TA are outlined. It is intended that this research will be useful for stakeholders in the foreign TA debate. In particular, this paper could serve as a "how to" training manual for socially conscious sustainable development experts and their hiring agencies.