Recent operations in Iraq and Afghanistan have given the US military an appreciation of both the importance and the challenges of working with and through host nation security forces in the aftermath of major combat operations. Secretary of Defense Robert M. Gates has indicated that these types of efforts will be an ongoing military requirement for the foreseeable future. The US military effort in support of Colombian security forces offers a different and a lesser known experience from which to learn: one that has been long-term, low-key, and seemingly successful. Between 1998 and 2008, Colombian security forces dramatically improved as they moved from what many considered the brink of disaster to being on the verge of victory. The Combat Studies Institute (CSI) is pleased to publish its 34th Occasional Paper, From El Billar to Operations Fenix and Jaque: The Colombian Security Force Experience, 1998-2008. Written at the request of US Southern Command, this study begins with an overview of the general security situation prior to 1998, then traces Colombian and US efforts during the Pastrana presidency and Plan Colombia, and concludes with the subsequent actions of the Uribe administration. In the final section, the author offers observations from the Colombian experience for those in the US military who will be called on to work with and through host nation security forces in the future. Although the Colombian experience offers no simple model to be replicated mindlessly elsewhere, it does offer observations and analysis that may be useful to the military professional struggling to address similar situations. Robert Ramsey's Occasional Paper not only provides a useful reminder of the inherent challenges for both host nation and US military personnel in those situations, but also shows that, given the right people, the right programs, and sufficient time, those challenges can be met successfully. Perhaps that is the best insight of all to be drawn from a reading of this work.