This article discusses a strand of research conducted by the Education Development Center, Inc. in collaboration with the National Center for Supported Electronic Text. The research investigated the use of an online vocabulary support tool, Visual Thesaurus, for middle school students with and without disabilities. Data were collected from 10 eighth grade inclusive classrooms using a randomized control trial to compare the impact of Visual Thesaurus and Merriam-Webster OnLine on vocabulary and content knowledge from two social studies textbook chapters. Data analysis revealed significant posttest gains for students in both conditions, but no significant difference between the two treatments. Discussion focuses on the need for online vocabulary support tools to align with student needs and teacher expectations. (Contains 3 tables and 3 figures.)