This chapter examines the relationship between body composition and race performance in several different types of endurance athletes, including cross-country skiers, rowers, runners, cyclists, swimmers, and triathletes. It presents normative data from various endurance sports and identifies differences in body composition across multiple age groups and training status, performance, and event duration. The ideal body composition varies with each sport but, in general, the less fat mass, the greater the performance. Although the measurement of body fat has been the prime focus of attention, many coaches working with elite athletes recognize that the amount and distribution of lean tissues like bone and muscle play an important role in determining sports performance. In male endurance athletes, fat-free mass (FFM) appears to be similar across different levels of runners with the largest lean mass associated with the lowest trained group. Anthropometric measurements such as skinfold and circumference measurements are the most used methods in the endurance athlete literature.