Class size reduction has been shown to, among other things, improve academic achievement for all students and particularly for low-income and minority students. With the No Child Left Behind Act's heavy emphasis on scientifically based research, adequate yearly progress, and disaggregated results, one wonders why all children aren't enrolled in small classes. Unfortunately, concerns about class size reduction's expense and misunderstandings about the research discourage class size reduction implementation. This document addresses these concerns by providing an overview of class size reduction financing that includes: (1) Definitions of class size reduction terminology with implications for class size research; (2) Guidelines for financing class size reduction implementation; (3) Case studies of successful class size reduction implementations at little or no extra expenditure; (4) A summary of class size reduction cost-benefit considerations; and (5) A comprehensive bibliography. This paper also presents finance case studies that provide actual data and examples of class size implementations. Critique of STAR Results Using Crane's (1998) Criteria is appended. (Contains 2 tables and 2 notes.)