Peer effects based on social network relations are prevalent in the diffusion of innovations.Based on a clear definition of peer effects,this paper presents a theoretical framework to study peer effects in the diffusion of innovations.Peer effects are split into information effect,experience effect and externality effect.This framework is applied to the case of the 10-year diffusion of a high-value crop in a rural community and the impact of the three effects on the diffusion of the high-value crop are analyzed in detail.The analyses indicate that the three effects dominate the diffusion process in its early,intermediate and late phases respectively and occur through different social networks.Information effect can motivate a very small number of individuals with a high willingness to innovate but is not able to provoke the majority to adopt innovation.Experience effect is relatively stronger and often facilitates the formation of a “critical mass”.Externality effect pushes the lagged to follow the suit.According to the theoretical framework and findings from the case study,suggestions for improving agricultural extensions and farmers’ adoption of agricultural technologies are made.