It is difficult to abstract a summary of a lifetime of work. I have chosen to discuss research on protein, calcium, and the effects of dietary fat and cholesterol on serum cholesterol and on my activities that led to the publication of the Dietary Guidelines for Americans. Among the conclusions from studies on protein and calcium is that reasonably healthy people are adapted to their current diets. People all over the world, for example, are raised on relatively low calcium intakes yet have less osteoporosis than those who consume western-style diets. They also appear to do reasonably well on low-lysine intakes. Attempts to define requirements need to allow for adaptation, and we need to determine whether such adaptations are beneficial or detrimental to health. The studies on serum cholesterol defined the role of the various classes of fatty acids. The publication of the Dietary Guidelines for Americans introduced a new era of nutrition and has radically altered nutrition policy, nutrition standards, and education.