An earlier study, 'Delinquency in a Birth Cohort,' served as a model for this research. Additional areas of interest in this study were the possibility of cohort differences generated by societal change, the possibility of an increase in the frequency and seriousness of police contacts by females, and possible verification of predictive statements on successive cohorts. Three birth cohorts (1,352 born in 1942, 2,099 born in 1949, and 2,676 born in 1955) were selected, careers were followed, and seriousness of criminal activity was measured. Study data were obtained from the Racine Police Department (Wisconsin) and from interviews conducted with cohort members. Reasons for police contact were initially coded into 26 categories, based upon police reports of juvenile and adult behavior. Data analysis reveals that females in the 1955 cohort have proportionately more police contacts and more serious contacts that do those in the 1942 and 1949 cohorts. However, they continue to have lower rates of contact and lower seriousness scores for police contacts than do males. While the proportion of females exhibiting continuity in their criminal careers is increasing, the proportion of males with career continuity has remained relatively stable but at a far higher level than that for females. The application of punishment to males does not appear to deter them from future police contacts, frequent police contacts, or contacts which generate high seriousness scores. These findings indicate that if police authorities decide to formalize their contacts with females as they have with males, female criminality will rise. Three footnotes and six tables are included.