Purpose: This paper examined the effects of parental drinking and smoking, parental warmth and hostility, and their interactions on offsprings' drinking and smoking over time. Methods: We used four waves of prospective longitudinal data collected from 218 males and 214 females who were age 15 at Time 1 and age 28 by Time 4. Growth mixture modeling was used to develop offspring trajectory groups of cigarette smokers and alcohol drinkers. Logistic regression analyses were conducted to determine whether parent behaviors could predict offspring heavy drinking and smoking trajectories. Results: Four drinking and three smoking trajectory groups were identified for females and males. Parent drinking rather than parenting behavior predicted heavy drinking by offsprings and mothers' drinking was a slightly better predictor than fathers' drinking for both daughters and sons. Fathers' warmth and hostility was the best predictor of heavy smoking by sons. Neither modeling nor parenting significantly predicted female heavy smoking. For the most part, parent modeling did not interact with parenting behavior to predict smoking or drinking in offspring. Implications: Parents affected their offspring's use of alcohol and cigarettes both through modeling and parenting behavior. However, the importance of modeling relative to parenting behavior differed by the type of substance. Prevention programs that focus on both the modeling of parental behaviors, as well as enhancing parenting skills, should be effective in influencing trajectories of substance use throughout adolescence and young adulthood.