The research reported here addresses two related questions in this area: (1) Have there been changes over time in sex differences in the disposition of police contacts with juveniles and adults? and (2) Do any observed changes account for increases in the female crime rate? Our analysis of data from 10,723 police contacts in a midwestern city during the period 1948-1976 found a trend toward a diminished sex difference in police dispositions of juvenile and adult misdemeanors and adult felonies. There was no evidence for a similar trend for juvenile status offenses of juvenile felonies. The findings also suggest that part of the apparent increase in female crime may be due to changes in official reactions to female offenders. (Publisher abstract)