This four-section report prepared by the Washington State Office of Financial Management examines the 1983-85 biennium budget forecasts for public common schools, total population and student movement in relation to economic cycles (over the past 2 decades), trends in public and private school enrollment (over the past 2 decades), and school dropout trends (1952 to 1982). Section I considers factors influencing the downward revision of the forecasts, development of K-12 average annual FTE enrollment forecasts, and private school assumptions. Section II shows that net population movements into and out of Washington and economic growth have been cyclical over the past 2 decades. Section III, on trends in public and private school enrollment over the past 2 decades, examines total K-12 enrollment, public enrollment, private enrollment, distribution of enrollment in public and private schools, and other private school data. Section IV examines dropout indicators and trends, factors relating to dropout trends, and the impact of dropouts on estimating average annual enrollments in grades 9-12. Thirteen tables and 11 figures include data on enrollment, cohort change, and grade succession rates. Further tables and a figure appear in the appendix. (PB)