This paper reports on a study of the curricular development in the ABC Unified School District in Southern California, over a span of 10-15 years, in response to an increase in limited-English-speaking students and legislative mandates. The case study was conducted through document review, observations, and interviews. The study focuses on key points at which decisions were made concerning instructional goals, staff development, teaching materials, and evaluation methods, emphasizing the change process. The study documents the conversion of the school district from one with low achievement scores among the Spanish- and Portuguese-speaking students and low staff morale to one that has gained a national reputation as exemplary in its application of principles of curriculum design. The report concludes with a proposed prototype curriculum model for bilingual education. (Author/MSE)