The Organization for Tropical Studies (OTS) is a consortium of 46 U.S. and 6 Costa Rican organizations that operates several field stations in the tropical forests of Costa Rica. The PI, Executive Director of OTS, proposes to acquire additional basic laboratory equipment for the La Selva Field Station and the recently established facility at Las Cruces. In addition, Dr. Stone has planned the construction of family housing for visiting scientists at Las Cruces (one duplex housing unit) and La Selva (two duplex units). The proposed housing construction will greatly expand the number of investigators who can initiate research at the Stations, and will accommodate younger scientists with small children as well as investigators with physical disabilities. More basic research equipment will allow the use of the Station by students and researchers to continue to expand. Continued growth and improvement in OTS is critical to the involvement of U.S. scientists and policy makers in tropical regions.