Among Harvard alumni aged 35-74 in 1962 or 1966, incidence rates of physician-diagnosed depression, together with suicide rates, were examined during a 23-27-year follow-up period, by antecedent physical activity habits and other personal characteristics. A total of 387 first attacks of depression developed among 10,201 alumni who survived through 1988; 129 suicides occurred among 21,569 alumni during follow-up through 1988. Depression rates were lower among the physically active and sports players, higher among cigarette smokers, unrelated to alcohol consumption, and higher among alumni reporting such personality traits as insomnia, exhaustion, cyclothymia, and self-consciousness. Suicide rates were largely unrelated to antecedent physical activity and alcohol consumption, higher among smokers, and substantially higher among men reporting the personality traits that predicted increased rates of depression.