Using data from a national study spanning 12 years, I examined the effects of several middle-school and high-school variables on completion versus non-completion of the bachelor's degree. All young people in the study had attended college with the purpose of attaining the bachelor's. Several variables had practically significant effects on degree completion, with the strongest effects from the academically intensive science and math courses that participants took in high school. The Long-Term Educational Development model was formulated from the findings; and separate analyses for Asian Americans, Latinos, African Americans, and Whites support the applicability of the model. The model identifies the salient influences on students' long-term educational development. It is offered as a guide for counseling, education-career planning, and leadership and advocacy for students' educational development. (Contains 3 tables and 1 figure.)