Community colleges are under pressure to increase completion rates and efficiency despite limited evidence of the economic consequences of different reform strategies. We introduce an economic model of student course pathways linked to college expenditures and revenues. Using detailed data from a single college, we calculate baseline efficiency and differences in efficiency for students who follow different pathways. We simulate changes in output, expenditures, revenues, net revenues, and efficiency assuming that the college meets particular performance targets. Findings indicate substantial differences in efficiency across pathways and significant differences in efficiency across strategies to help students complete college. They also suggest that increasing the completion rate is difficult and typically requires additional resources beyond the costs of implementing particular strategies. The model has wide practical application for community colleges. Appended are: (1) Measurement of the College Completion Rate; and (2) Outcomes for "U.S.A. Community College". (Contains 7 tables and 12 footnotes.)