In 1998, the Keystone Research Center published a comprehensive review of research on two high-profile ideas for raising educational achievement: lowering class size in the early grades and instituting private school vouchers. This report presents a research update, emphasizing results since early 1998. Over the past 2 years, the evidence on the achievement benefits of lowering class size in grades K-3 has grown stronger. The report discusses the Tennessee Student-Teacher Achievement Ratio program and the Wisconsin Student Achievement Guarantee in Education program. Evidence that private school vouchers raise student achievement remains weak. This report discusses the Milwaukee Parental Choice Program and the Cleveland Scholarship and Tutoring Program--two programs dealing with voucher issues. It also discusses implications of reducing class size for Pennsylvania. (Contains 85 references.) (DFR)