Over the last few decades, the theory that adult diseases begin in childhood has been widely discussed. Smoking, the most common underlying cause of death for adults in the United States, begins before the age of 18 years in the majority of adult smokers. Obesity has become the largest health problem in the United States, and the difficulty of long-term weight loss for obese children and adolescents means that many of them will be overweight as adults. The rationale for considering cardiovascular disease prevention efforts in childhood is compelling. Not only do risk factors track from childhood into adult life, but the development and progression of atherosclerosis, which often starts in childhood, are also directly related to the number of risk factors and their severity.