This paper summarizes a quantitative synthesis of studies of the effectiveness of interactive distance education using videoconferencing and telecommunications for K-12 academic achievement. Effect sizes for 19 experimental and quasi-experimental studies including 929 student participants were analyzed across sample characteristics, study methods, learning environment, learner attributes, and technological characteristics. The overall mean effect size was 0.147, a small positive effect in favor of distance education. Effect sizes were more positive for interactive distance education programs that combine an individualized approach with traditional classroom instruction. Programs including instruction delivered via telecommunications, enhancement of classroom learning, short duration, and small groups yielded larger effect sizes than programs using videoconferencing, primary instruction via distance, long duration, and large groups. Studies of distance education for all academic content areas except foreign language resulted in positive effect sizes. This synthesis supports the use of interactive distance education to complement, enhance, and expand education options, because distance education can be expected to result in achievement at least comparable to traditional instruction in most academic circumstances. A list of the studies is appended. (Contains 59 references.) (Author/AEF)