The question of what determines adult health and well-being is important to all countries. The Adverse Childhood Experiences (ACE) Study is a major American research project that poses the question of whether, and how, childhood experiences affect adult health decades later. This question is being answered with the ongoing collaboration of Robert Anda, MD at the Centers for Disease Control (CDC) and the cooperation of 17,421 adults at Kaiser Permanente’s Department of Preventive Medicine in San Diego, California. Kaiser Permanente is a multispecialty, prepaid, private health insurance system or Health Maintenance Organization [HMO]. The findings from the ACE Study provide a remarkable insight into how we become what we are as individuals and as a nation. They are important medically, socially, and economically. Indeed, they have given us reason to reconsider the very structure of primary care medical practice in America.