Since the 1998 publication of The Psychological Well-Being of Nonhuman Primates by the National Research Council, and the 1991 implementation of the 1985 Animal Welfare Act Amendment, many formal and informal nonhuman primate enrichment programs have been put into practice. Reports of their successes and failures, however, are few. All programs have at least two things in common: (1) They are best when designed and maintained by teams of individuals with species-specific expertise; (2) the members of those teams, the stakeholders, usually include principal investigators, animal care and use committee members, veterinarians, and animal care staff. Discussions in this article address general principles about enrichment, goals of such programs from the perspective of each of the major stakeholders, and recently published sources of related information. These discussions follow the central premise that enrichment should benefit all involved and "First, do no harm."