Regarding longitudinal studies of gang members, research has found that street gangs promote delinquent behavior and that gang membership is transitory, typically lasting no more than 1 year. The findings suggest that delinquent behaviors may stem more from the peer influence of gang membership than from the delinquent leanings of the gang members themselves. Regarding research on whether arrest and sanctions deter delinquency or make it worse, more than a dozen studies found that people who have been arrested are at least as likely to be arrested in the future as those who have not been arrested. Arrest resulted in similar or higher rates of later offending. These findings challenge deeply entrenched beliefs about deterrent effect of arrest and sanctions on adolescent offending. Regarding the effect of adolescent employment on offending, longitudinal studies have generally found that intensive work by adolescents (20 or more hours per week) increases delinquent behavior. Researchers believe that intensive work detracts from schoolwork, weakens parental supervision, and increases interaction with delinquent peers. Longitudinal studies also show that the quality of employment (challenging and satisfying work) may be more important for crime reduction than just having a job. Regarding the influence on delinquency of the assumption of adult roles, longitudinal studies show that of all the role transitions examined, marriage most effectively and consistently reduces deviance. What is not yet clear is why this is so.