Distance education is a significant topic of discussion within institutions at all levels of education. It is not only significant in terms of finances and student enrollment but also in terms of meaningful learning. The purpose of this study was to determine the relative effectiveness of three distance-education strategies for enhancing the science learning of 94 Midwestern elementary-school teachers participating in a 5-year professional-development project. The three distance-education strategies studied were interactive television with all presenters live in real time (live), interactive television with live discussions wrapped around videotaped presentations (video), and asynchronous, Web-based sessions with streamed videotaped presentations supported by interaction through discussion boards (Web). A repeated measures design was used to analyze the science learning and attitudes of the study participants. Analysis of variance of participants' postsession science scores yielded differences (p < 0.05) on multiple-choice and constructed-response science subscales. Participants in the live mode outperformed participants in the Web and video modes on all three assessment types (multiple choice, constructed response, and vignettes). Participants in the Web mode outperformed participants in the video mode on multiple choice and constructed response. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 43: 1019–1039, 2006