The Marine Biological Laboratory (MBL) is an independent, non-profit and educational institution and America's oldest private marine lab. Founded in 1888, the MBL offers a conductive environment for summer investigators and advance students from the U.S. and abroad to perform research. Diverse and abundant marine organisms found in surrounding waters serve as models for exploring fundamental life processes. In addition to being the summer home of American Biology, the MBL hosts major year-round research programs in cell and developmental biology, ecosystems studies, molecular evolution, neurobiology, and sensory physiology. NSF funds will be used to improve the mechanical systems of the Loeb Building, one of the MBL's five major laboratory buildings. Opened in 1969, Loeb serves as a prime focal point for research activities in experimental biology. It houses facilities for the Ecosystems Center, Boston University's Marine Program, and the summer research of the NINDS Laboratory of Neurobiology. In addition to housing research programs, Loeb is a major site where research training courses are conducted. However these activities, involving the use of electronic equipment to conduct state of the art research, require a level of environmental controls that the building's existing mechanical systems are incapable of providing. This modernization will consist of upgrading and repairing the existing ventilation systems and controls, and replacing the existing chiller with a more efficient unit. MBL has had a commitment to developing the nation's intellectual capital, particularly in the area of basic biology, and has been a long term beneficiary of partnerships with a variety of institutions across the nation. This project will help strengthen the MBL infrastructure, which will sustain the tradition in Loeb, and campus wide, well into the next century.