Written for school districts with one high school, this report is designed to help communities plan for fewer students at the high school level. The report is divided into four parts. Part I discusses the nature of the problem, the difference between elementary and high school decline, and the special case of the single high school district. Part II presents numerous strategies which are available and should be explored, together with examples and indications of where they might be appropriate. It discusses strategies within the school system, strategies in cooperation with other school districts, and strategies using educational and community institutions outside the school system. Part III explores issues and concerns which are common to many school districts considering decline and strategies from the perspective of different constituents. It covers the role of the high school as a community institution, the comprehensive high school, high school faculty, high school space and facilities, scheduling, transportation, working with neighboring districts or other institutions, program costs, and roles of the states. Part IV offers concrete advice on how to plan for decline. It discusses planning, defining problems and goals, setting priorities, exploring and evaluating options, and developing a plan of action. (Author/CM)