This reference guide describes the implementation and use of mixed-age classrooms in Oregon. Those schools that wished to be included provided information on a prepared form. Responses from 94 elementary schools from 23 counties are presented. Each school's profile includes information on school statistics, a description of the program, how the program was implemented, the role of parents, advice, resources available, and a visitor policy. Synthesized and summarized separately at the end of the guide are advice to schools implementing mixed-age programs, guiding principles and best-practices, developmentally appropriate practices, instructional strategies, and types of teacher role and class management. (TM)