Barriers to the implementation of technology-based materials in elementary school mathematics classrooms were studied using naturalistic inquiry and multiple methods of data collection in keeping with ethnographic principles. Qualitative data were gathered from interviews with teachers and administrators, reviews of school documents, observations of classrooms, and analyses of teacher-written responses to open-ended questions. Quantitative data were obtained from classroom observation checklists, lesson and workshop evaluation forms, and two self-report measures of teacher attitudes. The Supplementary Mathematics Materials for a Technological Society (SMMTS) program, which contains calculator and microcomputer activities, was developed to supplement mathematics curricula in grades 1 through 5. The SMMTS develops elementary school mathematics curriculum materials that incorporate technology and studies the effects of these curricula in the classroom. Implementation of the SMMTS was studied in 16 teachers' classrooms in one school district. Major barriers to calculator use were: teacher characteristics; characteristics of the material; and organizational arrangements. Factors that interfered with computer use were: the requirement for computer expertise; difficulties with the equipment; and difficulties with the whole-class demonstration format. The ethnographic techniques offered a valuable perspective on these barriers. One table and three figures present study results. A 26-item list of references is included. (SLD)