The rate of offending of active offenders (i.e., lambda) varied substantially as a function of age, increasing monotonically with age. Lambda, however, was not related to the age at first offense. In fact, the average lambda was amazingly constant at each individual age level regardless of the age at which offending began or desisted. Results are discussed in the light of age-crime curves known from other data sets and from the perspective of developmental changes in the rate of offending as youths grow older. 4 tables, 1 figure, 16 references. (Author abstract)