The current debate about class size is not centered on whether smaller class sizes are desirable. Rather, the debate is whether the costs involved are the best ways to spend taxpayers' monies. This analysis addresses this question for the state of Florida. Using the Florida Comprehensive Assessment Test as a measure of educational achievement, a state data set containing information on all elementary schools was used to examine which government-funded inputs were most cost effective. Using a three-step methodology leading to a cost effectiveness analysis, this article finds that reducing class sizes is the most expensive of state inputs that affect achievement scores. Varying the mix of school personnel (administrators, teachers, and teacher aides) and investments in teacher quality (training and experience) are shown to produce the same results (raising test scores) at a lower cost than the reduction of class sizes. (Contains 5 tables, 3 figures, and 12 notes.)