DNA evidence is playing a larger role than ever before in criminal cases throughout the country, both to convict the guilty and to exonerate those wrongly accused or convicted. In light of this increasing role, NIJ and OVC developed this brochure to describe the value of DNA evidence for victim service providers so that they can understand the potential significance of DNA evidence to their clients' cases. It also discusses evidence collection, contamination, and preservation issues; the interpretation of DNA test results; and the CODIS index.