Study objectives were (1) to construct a conceptual model to relate incremental educational achievement of individual students during a 2-school-year period to economic inputs of the school, student inputs, and family inputs during that period and (2) to use the model as a basis for generating an economic factor model for the school unit. To test the model empirically, data were obtained on students from 5 high schools in south-central Kentucky. School budgetry and enrollment data, student test data, and student and family background data obtained by student questionnaire were subjected to multiple correlation-regression analysis. Statistically significant and positive relationships were found between incremental student achievement in basic subjects and (1) student's mental ability, (2) opportunity cost of student time investment in formal education, and (3) student's academic commitment or intensity of effort; an inverse relationship was found involving the number of job hours worked by the student during the 2-school-year period. A statistically significant and positive relationship was found between average incremental student achievement and per-class expenditures on teacher's salary; no statistically significant relationship was found involving average class size. Due perhaps to peculiarities of the sample, no statistically significant relationships were found involving either family variables or investment either in instructional equipment or plant facilities. (BO)