Lillian Wald invented public health nursing in 1893, making this year the field's centennial. One of nursing's visionaries, Wald secured reforms in health, industry, education, recreation, and housing. This historical inquiry examines three of Wald's critical experiments, each of which illuminates the past of public health nursing and its contemporary dilemmas: invention of public health nursing itself, establishment of a nationwide system of insurance payments for home-based care, and creation of a national public health nursing service.