This report from the Charter School Achievement Consensus Panel, a group of nine researchers convened by the National Charter School Research Project, examines the existing research on student achievement in charter schools and details how future research could be improved. The panel reviewed and rated more than 40 evaluations of charter school performance released between 2000 and 2005. Studies evaluating charter schools nationally or across states were found to be "fair" to "poor." Two key findings are that: (1) no one research method or approach is problem-free; and (2) the results of studies focused on one kind of charter school cannot be generalized to all charter schools. The panel offers guidelines for local, regional, and national studies and recommends that the research community consider the pattern of results from multiple studies instead of relying on a single study for definitive results. This White Paper is the first in a series of reports from the consensus panel, all of which will be concerned with assessing and strengthening the evidence about charter school outcomes. Appended are: (1) List of Charter School Studies Included in Literature Review; and (2) Details on the Literature on Charter Schools. (Contains 6 tables and 3 figures.) [Principal drafters of this report were: Julian Betts and Paul T. Hill.]