In recent years, information resellers--companies that collect and resell information on individuals--dramatically increased the collection and sharing of personal data for marketing purposes, raising privacy concerns among some in Congress. Recent growth in the use of social media, mobile applications, and other technologies intensified these concerns. GAO was asked to examine privacy issues and information resellers. This report addresses (1) privacy laws applicable to consumer information held by resellers, (2) gaps in the law that may exist, and (3) views on approaches for improving consumer data privacy.