A process of developing and testing an instructional methodology called interactive radio instruction (IRI) was begun in 1986 in order to improve the quality of primary school mathematics in Bolivia. When the development phase was complete and implementation well under way, management of the resultant Radio Learning Project (RLP) passed from the non-governmental organization (NGO), Fe y Alegria, to the Ministry of Education and Culture (MEC). Today, seven years after the initial pilot, approximately 600,000 primary-school children have enrolled in the RLP, renamed PARI; more than 8,000 teachers have been trained and certified in the IRI methodology, and in 1992, Radio Math achieved national recognition as the "official" mathematics program of Bolivia. This case study assesses how NGO management sustained RLP continuity, describes how broad-based teacher support laid the base for institutionalization, and looks at how IRI has revolutionized education in Bolivia. Rather than dwell on issues related to methodology or impact, the study assesses the sustainability of PARI from the sociological perspective, focusing on the issues of participation of people and systems key in driving national diffusion and sustainability. An appendix provides a chronology of events. (Contains nine references.) (Author/MAS)