This report analyzes the economic and social costs of the high school dropout problem in Montana from the perspective of a state taxpayer. The majority of the authors' analysis considers the consequences of this problem in terms of labor market, tax revenue, and public service costs. In quantifying these costs, the authors seek to inform public policy, estimate the benefits of addressing the problem, and engage state citizenry in the problem's remedy. The individual and societal costs associated with dropping out of high school in Montana are profound, with particular implications for the state's American Indian student population. That said, the potential benefits from reducing the dropout rate are equally profound. Their analysis of these costs and benefits reveals the following findings: (1) According to the Montana Office of Public Instruction (MOPI), 1,989 students, or 16.1% of he entire class of 2008, dropped out of high school; (2) Dropout statistics for Montana's American Indian students are alarming. Only 63% of American Indians in the class of 2008 graduated high school on time; (3) On average, Montana high school dropouts work close to eight fewer weeks per year than those whose highest degree is a high school diploma or GED; (4) In extrapolating the annual costs of dropouts to Montana's economy, the authors estimate that the average high school dropout is earning $5,868 less per year than they would if they had graduated; (5) When comparing the average Medicaid subsidies of a high school dropout to the average of an expected high school graduate, they arrive at an estimated increase in annual costs of $616 per dropout; (6) Using the findings of a prior econometric study on the causal relationship of high school graduation to the likelihood of incarceration, the authors estimate the average annual incarceration costs of Montana's 36,788 dropouts would decline by $268 per person had they graduated from high school; and (7) The authors estimate that each prevented dropout will result in $32,402 benefits to the state over that individual's lifetime. (Contains 8 tables, 8 figures and 32 notes.)