The market in trafficked children bought and sold for sexual exploitation is one of the most inhumane transnational crimes that appear to have been facilitated by globalization and its many effects, such as growing disparity in wealth between North and South. Child sex trafficking (CST) in the Greater Mekong Subregion (GMS) is an extremely complex problem, deeply rooted in historical injustice, gender inequality and poverty. In addition to the complexities of the child trafficking issue, the organizations that seek to combat CST are themselves not always a united force and display their own internal and inter-agency complexities. The purpose of this paper is to examine some of the key complexities of responding to CST in Thailand and Cambodia.