Friendship tie choices in adolescent social networks coevolve simultaneously with youths’ cigarette smoking and drinking. We estimate direct and multiplicative relationships between both peer influence and peer selection with salient parental factors affecting both friendship tie choice and the use of these 2 substances. We utilize 1 sample of 12 small schools and a single large school extracted from the National Longitudinal Study of Adolescent to Adult Health. Using a Stochastic Actor-Based modeling approach over 3 waves, we find: (a) a peer selection effect, as adolescents nominated others as friends based on cigarette and alcohol use levels across samples; (b) a peer influence effect, as adolescents adapted their smoking and drinking behaviors to those of their best friends across samples; (c) reciprocal effect between cigarette and alcohol usage in the small school sample; (d) a direct effect of parental support and the home smoking environment on adolescent friendship tie choice in the small school sample; (e) a direct effect of the home smoking environment on smoking across samples; (f) a direct effect of the home drinking environment on alcohol use across samples; and (g) a direct effect of parental monitoring on alcohol use across samples. We observed an interaction between parental support and peer influence in affecting drinking, and an interaction between the home drinking environment and peer influence on drinking, in the small school sample. Our findings suggested the importance of delineating direct and synergistic pathways linking network processes and parental influence as they affect concurrent cigarette and alcohol use.