High blood cholesterol is a major risk factor for coronary heart disease. An abundance of data accrued over the past several decades indicates an important role for dietary saturated fatty acids and cholesterol in modulating blood cholesterol levels. These observations form the basis for current dietary recommendations aimed at reducing CHD. While there is general consensus that saturated fatty acids and cholesterol should be reduced, confusion still exists with respect to optimal levels of other dietary components. Uncertainty also exists with respect to individual variability in response to dietary intervention. While it is feasible to study lipid parameters and other factors in humans on well controlled 'natural' diets over extended periods of time, no single center has the facilities to recruit and study sufficient numbers of subjects to draw meaningful public health conclusions. In order to do such a study, subjects must be recruited and studied in multiple centers using identical protocols so that data can be pooled. This proposal would establish at the University of North Carolina's Collaborative Studies Coordinating Center (CSCC) a coordinating center for a multicentered, standardized, well controlled dietary feeding study in which a series of experimental dietary modifications will be tested. A key component will be to establish a food analysis control center to verify composition of the experimental diets. In addition, the CSCC proposes to: (a) collaborate with investigators in the design of a cost-effective study protocol; (b) lead in the creation of appropriate data collection instruments; (c) provide administrative support (e.g. meetings, arrangements and minutes, central communication, manuscript production); (d) develop and implement a data management system; (e) train clinic staff, write a detailed manual of operations, and provide clinic support (e.g. Protocol interpretation) during the study; (f) monitor and maintain data quality at clinics and laboratories; (g) produce statistical reports for investigators and monitoring board; and (h) coordinate publication efforts. Specific plans for meeting these aims, as well as the CSCC's experience in such activities for other collaborative cardiovascular research,are detailed.