The offense and personal histories of the 442 males were examined. The frequency of crimes was evenly distributed over the course of the year, although considerable fluctuations occurred. Males born in the period between April and June were more likely to commit offenses between November and December and less likely to do so between March and April. Those born between July and September committed offenses more often in September and October and less often in November and December; they were more likely to commit offenses in a month closer to their birth month than in a month further away from it. Males born between October and December tended to commit crime more often if they were older than 24 and less often if they were younger. In general, those born during the spring and summer committed crimes at a relatively younger age than those born during the fall and winter. The occurrence of crime may be affected by other factors including the availability of victims; social situations; and the age, education, and social class of the perpetrators. Periods of the year are, however, corelated with physical and social factors. Additional study in this area is needed. Tabular daa and 41 references are included.