In this paper we examine period or secular changes in the association
between drug use and delinquency among Ontario adolescent students bet
ween 1983 and 1991. The results show that during this period drug use
and drug-selling declined significantly, whereas reported non-drug-rel
ated delinquency increased. In addition to differing secular trends in
rates of drug use and delinquent behaviour, the association between t
he two behaviours weakened. There was a steady decline in the correlat
ions. between drug use and delinquency across time, and the typologica
l patterning of drug use and delinquency changed significantly.