The interrelation between parental drug use and parental personality a
nd the effects on 18-month-old children's adjustment were examined. Da
ta on the parents were available at four points in time: Time 1 at mea
n age 6.1 years, Time 2 at mean age 13.7 years, Time 3 at mean age 16.
4 years, and at Time 4 at mean age 22.2 years. Data on their toddlers
at 18 months of age were also available. Structured interviews were us
ed to assess personality and drug use and the toddlers' adjustment. Ti
me 3 parental personality traits were related to Time 4 personality tr
aits, which in turn were related to toddler adjustment. The influence
of parental alcohol involvement (Time 3) on toddler adjustment was med
iated by parental personality (Times 3 and 4) and parental alcohol pro
blems (Time 4). Interactive effects demonstrated that protective paren
tal personality traits (nondrug conducive) enhanced the effects of low
parental drug use, resulting in the highest amounts of toddler adjust
ment. There are significant pathways between parental personality and
drug use and toddler adjustment. Parental protective factors enhance t
he effect of parental low drug use on toddler adjustment.