This study examined the effect of school size on a set of indicators related to input and outcome variables from high schools in the state of Virginia. Research suggests that the size of high schools may be related to school effectiveness. Is there a difference between educational inputs and outcomes of small and large high schools in the state which is related to size? The study examined ten measures of inputs and outcomes to determine if there is a significant difference in the indicators of school success which can be attributed to school size. The study focused on the following ten indicators: The percentages of students earning advanced studies diplomas, the percentage of students who go to a four-year college after graduation, the educational background of teachers in the school, the level of teacher experience in the school, the number of courses offered to students in the school, the percentage of students who are at or above the 75th percentile on the composite score of the 11th grade standardized test, the percentage of the 11th and 12th grade students who took the SAT test and scored at or above 1100, the percentage of students who miss ten or fewer days of school in a year, and the percentage of students who dropout of school. Separate analysis of covariance (ANCOVA) tests were used for each indicator of educational input or outcome. A socioeconomic status index was used as a covariate in all of the tests. Statistical Package for the Social Sciences (SPSS) software was utilized for all computations. The study produced evidence that small high schools and large high schools are significantly different over a range of indicators of school success. In seven of the ten indicators compared, large schools were found to have an advantage over small schools. No significant difference was found between small schools and large schools in only three of the indicators tested, teacher experience, attendance, and dropout rate. Large high schools were not found to be at a disadvantage in any of the indicators included. / Ed. D.