Genetic data can provide a powerful tool for those interested in the ecology and management of wildlife, especially when it is combined with behavioral, demographic, or spatial information. Although the full potential of genetic approaches to the study of wildlife populations has yet to be realized, the application of genetic analyses is becoming increasingly feasible and cost-effective. This is due primarily to recent advances in the number and types of genetic markers available, the development of sophisticated data analysis methods, and increased automation of laboratory instrumentation. These technological advances have broadened the list of questions that can be answered with genetic data, allowing inference at multiple levels of resolution (inter-individual to inter-specific) and temporal and spatial scales. Genetic data can be used to assess mating systems, hybridization, gene flow, effective population size, and population viability. Genetic data can also be used to define management units; identify individuals, sex, and species; and to provide insights into demographic patterns associated with the reduction and expansion of populations. All of these factors are either related to a species' ecology or provide important information for management and conservation. We describe some applications of genetic data, discuss processes affecting genetic variation within and among populations, and provide an overview of genetic terminology and how genetic variation is measured. As genetic methods become progressively more accessible and adaptable to an ever-widening array of questions, it is expected that they will play an increasingly important role in the ecology and management of wildlife.