In the 1960s, patient advocacy groups were instrumental in efforts to mandate state testing of newborns for phenylketonuria (PKU), a recessively inherited disorder of phenylalanine metabolism. Advocacy groups have continued to actively lobby for the expansion of screening to other conditions detectable in newborns and, currently, for states' adoption of a uniform core screening panel. They have also been generally favorable to the offer of fee-based supplemental screening services. In the early years of newborn screening, groups such as the National Association for Retarded Children (NARC) were strongly imbued with a public-health ethic. This ethic has apparently eroded over time as the result of both broad social changes and the increasing entanglement of such groups with pharmaceutical and biotechnology companies. A history of newborn screening reveals both continuities and discontinuities in the agendas and funding of patient advocacy groups and in their rhetorical strategies. In particular, it demonstrates that there have always been tensions as well as partnerships with medical and other professionals, although the nature and intensity of the former have been affected by advocacy groups' increasing numbers, resources, and cultural authority. It also illuminates differences that have emerged as advocacy groups have informally allied with industry and adopted new rationales in support of access to testing.