This contribution asks which factors predict early school leaving, non-completion, and completion in upper secondary education in Norway? The data comprises survey and public register data for 9,749 students. The analyses identified three major groups of variables predicting early school leaving, non-completion, and completion: social background, earlier school performance, and academic and social identification, and engagement with the school and its content. The far most predictive variable was earlier school performance, as measured by grades from last year of compulsory education. On this basis the study suggests that measures to prevent early school leaving and non-completion must build upon the fact that the students enter upper secondary education with very different prerequisites to master the demands that meet them. (Contains 6 figures, 3 tables, and 1 footnote.)