Previous research has shown there to be a relationship between criminal peers and an individual's antisocial behavior and attitudes. Social literature lacks however empirical support for social identity theory, which suggests social identity serves as a mediator in the development of attitudes. Rather than a direct relationship where criminal peers influences the presence of criminal attitudes, this research suggests that criminal peers actually influences a mediator (i.e. an individual's social identity), which in turn influences their criminal attitudes. Thus, this mediation serves to clarify the nature of the seemingly apparent relationship between peers and attitudes. The current study, then, attempts to test the relationship between an individual's criminal associations and their criminal attitudes by introducing the individual's social identity as a mediator among individuals currently on probation or parole participating in a reentry program. This is done through the application of a survey constructed of three previously validated measures, and analyzed in two steps: firstly at the measurement level through confirmatory factor analysis; and secondly at the structural level through structural equation modeling.