Developing countries have been expanding educational enrollments, especially at the lower levels. But for any given level of efficiency, increased enrollments require increased resources to maintain quality. This paper explores the negative impact of enrollment expansion on school conditions and learning, using a cross-district time series analysis of Tamil Nadu, India. In the past two decades, the Tamil Nadu government has adopted numerous measures to increase enrollments: setting up a primary school in every village with more than 1,000 inhabitants (recently lowering that threshold to 500); providing free lunches, uniforms, and books; and offering incentives to encourage girls' schooling. Between 1977 and 1992, 2,700 primary schools were added, and enrollment rates increased to 101 percent for primary school, 96 percent for middle school, and 47 percent for high school. However, the number of teachers increased by only 4 percent during this period, and pupil-teacher ratios in primary and middle schools ranged from 39:1 to 54:1 in 1992. In addition, many new rural schools had no buildings or only meager facilities. Educational quality, as measured by the pass rate on the statewide 10th-grade examination, suffered, particularly in districts with the fastest enrollment growth. Districts with a high proportion of privately managed schools performed better. Policy changes such as greater use of private management and finance and greater local discretion in publicly-managed schools might improve the situation. An appendix examines the influence of family and village characteristics and state policies on enrollments. (Contains 19 references.) (SV)