In extending the current knowledge base of resiliency, this study used a national probability sample of adolescents and investigated the independent and cumulative effects that a variety of protective factors had on individuals’ probability of being resilient against self-reported delinquency and drug use. The study is discussed in four chapters. Chapter 1 begins with a discussion of the relevance of criminal career research to crime control policy and contemporary theoretical developments, followed by a review of the literature on risk factors, a core concept in resiliency research. Three substantive areas were covered: (1) a discussion traced the scholarly origin of risk-factor research; (2) a review of the research investigated where (i.e., family, school, and neighborhood) and when (i.e., childhood, adolescence, and adulthood) different risk factors emerge; and (3) the cumulative effects that criminogenic risk factors have on the probability of engaging in delinquency. The chapter traced the origins of the concept of resiliency and reviewed relevant empirical research. Finally, the research strategy was outlined using the National Longitudinal Survey of Youth, Child-Mother data set (NLSY). Chapter 2 described the NLSY method used to empirically examine resilient youth over the life course, how the sample was selected and its characteristics, the measurement of the core concepts of resiliency research, and the statistical approaches used. Chapter 3 presented research findings by first presenting data on the relationship between risk and self-reported delinquency and drug use. The data suggested that as risks accumulated the prevalence of delinquency and drug use increased. Second, findings were presented on the relationship between protection and delinquency and drug use. The data suggested that the accumulation of protective factors had an inverse effect on the prevalence of self-reported delinquency and drug use. Chapter 4 summarized the major findings of the research, implications of the findings, and research limitations. The data provided support to the detrimental effects related to the accumulation of risk. As risks measured early in the life course accumulated within an individual, their likelihood of participating in illegal activities significantly increased. Evidence suggested that factors within the individual (i.e., self-esteem), the family (i.e., supportive milieu), and the community (i.e., organizational involvement) serve as important protective factors that promote resiliency. The results of the research suggested that strategies to intervene in the lives of adolescents should be broad-based and involve attention to modifying the dynamic risk and protective factors. Focusing on the positive aspects (protection) of the lives of individuals was likely to return additional benefits over and above the attention only to the negative aspects (risk). Research limitations included: (1) delinquency measures and resiliency measure were left censored; (2) due to the methodological design, individuals were interviewed in 2-year intervals but only asked about their delinquent involvement over the preceding year; (3) the isolation of the high-risk group was based entirely on factors that occurred early in the life course; (4) investigation of whether protective factors were invariant across developmental periods could not be examined because of the small proportion of individuals in adulthood; and (5) the data did not permit the investigation of the effects of a number of other protective factors shown to influence resiliency. Future research on protective factors and resiliency are discussed. Tables, appendices, references