High quality reprint of this recently declassified 1975 study. The Air Staff tasked Project CHECO to write continuing reports on counterinsurgency in Thailand. Normally, the first work in a continuing report series describes the overall situation, and subsequent reports provide annual or biannual updates. Underlying details about the Thai insurgency, however, have slowly been coming to light over the past few years, therefore, counterinsurgency has necessarily continued to evolve and past CHECO works on counterinsurgency have been limited to reporting the specific end events of force and counter force. This study attempts to delimit the background to the Thai insurgency and counterinsurgency. Preliminary surveys of the literature and data available indicated that insurgency and counterinsurgency in Thailand have been well documented but that pertinent information is scattered throughout a multitude of separate reports and studies by many agencies. Consequently, one must read numerous publications to become enlightened on all but the most narrowly focused insurgency/counterinsurgency topics. This report attempts to integrate in one volume for the staff officer a broad background and wide perspective of insurgency and counterinsurgency in Thailand. It extracts from many of the completed works and indicates where more detail can be found. It avoids duplicating lengthy explanations already published, avoids citing detailed statistics on armed conflict which are all too often misleading indicators, and avoids discussing personalities which have been important but are left to more exhaustive studies. Due to the nature of its comprehensive approach, this report only indicates the complexities of the Thai insurgency/counterinsurgency and sketches in broadest terms the cultural heritage of the Thai.