Statistics are analyzed for changes in the incidence of official processing (cautions and findings of guilt) from 1964, the first year in which the age of criminal responsibility was 10, to 1978, the last year for which Home Office criminal statistics are available. The incidence of findings of guilt for 14 to 16 year-old males increased from 2.91 per 100 in 1964 to 5.26 in 1978, an increase of about 81 percent. However, taking into consideration changes in legislation, the increase without the legislation would have been about 50 percent. Between 1964 and 1978, the number of 10 to 13-year-olds found guilty decreased about 30 percent, while the corresponding number of 14 to 16-year olds increased about 50 to 60 percent, and the corresponding number of 17 to 20-year olds increased by more than 100 percent. The incidence of official processing increased in all cases, with the greatest increases being for females and for the older age groups. Other statistics indicate that after the introduction of the cautioning scheme, there was a widening of the net of arrested juveniles, especially in the youngest (10 to 13) age group. Figures on findings of guilt suggest that 10 to 13-year olds were diverted, but not 14 to 16-year olds. The research suggests that the introduction of the police caution caused a great increase in the number of officially processed juveniles and after allowing for the important factors of juvenile attitude, police cautions were no more successful than findings of guilt in preventing recidivism. The adoption of police cautions seems to have had more undesired than desired effects. Tables and 23 references are provided.