Similarity between deviant peers: Developmental trends in influence and selection*

The association between an adolescent's own behavior and that of his or her peers remains a key empirical finding in the study of delinquency, and this similarity is often explained in criminology by invoking processes of social influence and homophily. Adolescence is a period of rapid change for both individuals and their surroundings, however, and influence and homophily are often discussed without attending to their development over time. In the current study, I employ longitudinal social network models to estimate social influence and homophily related to alcohol and cigarette use and to determine whether there is change in the strength of these processes. Furthermore, I test whether the broader social environment conditions these processes and their observed changes. The results from this study indicate that although influence from peers decreases from early to mid-adolescence, homophily on drinking and smoking increases. There is also evidence that school-level opportunities and expectations affect social influence and homophily but do not account for the average changes observed in these processes.