Becoming Deviant describes a process by which people move from an affinity for certain prohibited behaviors to full-blown deviance. This process includes affiliation with circles and settings that include or sponsor offenses, followed by understanding and identification of the offenses as prohibited behavior by the transgressor. The process can be summarized as affinity, affiliation, and signification. The sequential process Matza describes allows for non-recurrent offending behavior, recidivism, and offending again. His perspective is motivated by the view that criminological theories do not explain a number of the fundamental empirical features and nuances known to be associated with delinquency. This includes the frequent termination of delinquent behavior at the onset of adulthood, the often conformist nature of delinquent behavior, and the large numbers of non-delinquents that are often found in otherwise high-delinquency areas. In Becoming Deviant Matza reasons that most, though not all, delinquent behavior constitutes relatively uniform phenomena that is developmental in character. Individuals proceed from trivial to more serious infractions. He argues that delinquent behavior represents youths searching for adventure and is accompanied by withdrawal from conventional values and associated behavior. Matza further claims that many delinquents are not fully committed to a delinquent lifestyle, and this explains why delinquent behavior often ends with adulthood. Matza’s compelling and integrated theoretical explanation makes this a classic in the increasingly sophisticated criminological literature. Thomas Blomberg’s new introduction shows why Becoming Deviant remains of central importance to the field.