Physical performance of Finnish adolescents (33 females, 44 males) with moderate intellectual disability (ID) was studied over a 30-year period. This study is an extension of Lahtinen's previous work on documenting the performance of individuals with intellectual disabilities over time. This study consisted of analyzing data from a total of four data collection periods (1973, 1979, 1996 and 2003 in which participants ranged in age from 11-16, 17-22, 34-39 and 41-46 years old, respectively). Improvement from early to late adolescence, and decline during adulthood in abdominal strength/endurance, static balance, and manual dexterity were identified. The male adults with ID were moderately overweight (BMI), but the females with ID were obese. The IQ effect was significant on balance and manual dexterity. The gender differences in adulthood were significant, but differences were not noted for DS when controlling for IQ. (Contains 4 tables.)