Digital collections of social science data have existed since the early years of computing. Data archives and data libraries, created by government agencies and academic institutions, have flourished since the mid-1970s. These repositories have provided preservation and access to ever-growing digital collections of social science data. Highly specialized requirements for both maintaining and using social science data collections fostered a specialized network of repositories and providers. These organizations coordinated their activities to assist researchers in identifying, acquiring, and understanding such digital information.