The experiences of five California school districts in implementing English immersion instruction for all limited-English-speaking students are described and compared. The districts range from populous urban settings to small, isolated rural communities. The first part of the report profiles the five districts, and the second part sets forth three significant issues that made planning for English immersion difficult: defining the terminology used in designing, implementing, and describing the programs; specifying the characteristics and elements of immersion instruction so they could be applied consistently; and designing the program itself, including population, placement, proportion of instruction in English, and nature and quantity of contact with native English speakers. The third part outlines some program implementation issues that occurred in all of the districts, and how they were resolved. The article concludes with a description of the common evaluation design used in all of the districts and presents some preliminary student achievement data. (Contains 16 references.) (MSE)