In this project a re-synthesis of the research dealing with student performance in new science curricula was conducted using the refined statistical procedures proposed by Hedges (1981, 1982a, 1982b, 1982c) and Hedges and Olkin (1985). The results of the re-synthesis generally supported the conclusions drawn in the earlier meta-analysis by Shymansky, Kyle, and Alport (1983); i.e., that the new science curricula of the 60's and 70's were more effective in enhancing student performance than traditional textbook-based programs of the time. But the re-synthesis also revealed some notable differences as well. For example, in the re-synthesis mean effects were significantly positive on four performance clusters (achievement, process skills, problem solving, and attitude) compared to seven clusters in the earlier analysis, and then by a smaller margin (the 1981 mean was 0.34 and the 1986 mean was 0.25). In one case (related skills), the mean effect changed from a +0.25 (significant at the 0.05 level) to –0.10. But perhaps more important than any particular change in the many analyses performed, the application of refined statistical procedures in the re-synthesis yielded results of greater precision than those generated in the original study. Thus, it is recommended that the data generated in this re-synthesis be used in any discussion of the effects of the new science curricula on student performance.