Peer Networks and the diffusion of intervention outcomes

This chapter begins by reviewing how interventions shape-and are shaped by-peer networks. To start, interventions can change relationships and behavioral dynamics within peer networks. At the same time, peer networks can support (or undermine) intervention effectiveness and promote (or hinder) the diffusion of intervention outcomes beyond those who participated in the intervention. In addition, prevention scientists can use information about peer networks to design interventions that can accelerate behavior change and diffusion processes. After reviewing past research, four studies are described that used data from the PROSPER (Promoting School-community-university Partnerships to Enhance Resilience) Peers Project to test the link between substance use preventive interventions and school-based friendship networks. Study 1 demonstrated that after participating in PROSPER, prosocial adolescents became more central members of their friendship networks. Studies 2 and 3 explored when and how friendship networks facilitated the diffusion of intervention outcomes from adolescents who participated in a family-based intervention to those who did not. Study 4 used simulations to estimate the likely effectiveness of five network-based strategies for selecting intervention participants. The chapter concludes by arguing that prevention scientists, program facilitators, and school staff should consider peer networks when designing, implementing, and evaluating interventions.