Among males in the United States, death rates from suicide increase consistently with age throughout life, but among females, rates decline after the age group 50-54. This difference is seen in only a few other countries and possibly reflects pressures exerted on the sexes differentially by a particular type of social system. Although rates for Negroes in general in this country are lower than those for whites, among Negroes up to age 35 living in the north rates are as high as those of whites living in the same region; over age 35 the differences are less than those observed in the south. Presumably, therefore, the difference between rates for Negroes and whites results from environmental differences in living conditions. Age and sex specific trends in suicide rates for whites are examined for the period 1920-59. The trends for females show no marked fluctuations, but since the early 1930''s they have been generally downward, most strikingly in the age group 15-24 where rates in 1959 were about one-third of those in 1933. For males, however, several major fluctuations occurred. Rates for all age groups, but particularly in the range 45-74, reached a peak at the height of the depression (1933) and declined as the depression receded. During World War II rates declined in all age groups. Subsequent to World War II trends in the age groups 35-74 have followed closely trends in the percentage of the labor force unemployed. The data strengthen the hypothesis that unemployment may be an important determinant of suicide rates among males, particularly in the age groups in the 35-74 range.