Within the literature there has been a call for the integration of science, technology, engineering, and mathematics (STEM) disciplines. Little research has been conducted to investigate the effects of integrative approaches among STEM subjects. The purpose of this study was to synthesize findings from existing research on the effects of integrative approaches among STEM subjects on students' achievement. Meta-analysis was employed to address the research questions of this study. Twenty eight studies were selected and thirty three effect sizes were calculated to examine the effects of the integrative approaches among STEM subjects. The overall effect size was 0.63 which is a medium effect size. With respect to the grade levels, the effects of integrative approaches showed the largest effect size of 1.12 at the elementary school level and the smallest effect size of 0.33 at the college level. Regarding the types of integration, STEM, the integration of four subjects, presented the largest effect size of 1.76 and E-M and M-S-T showed the smallest effect size of 0.03. In addition, the achievement through integrative approaches, STEM achievement showed the highest effect size of 1.76 and mathematics achievement showed the smallest effect size of 0.26. The results of this meta-analysis reveal that the integrative approaches among STEM subjects have positive effects on the students' achievement. Further empirical research on the effects of STEM education needs to be conducted to confirm the findings of this meta-analysis. (Contains 1 figure and 5 tables.)