This annotated bibliography identifies issues affecting the on-line teaching environment by assembling a variety of quantitative and qualitative studies. Studies in the bibliography are divided into two major categories: (1) topical studies, which contain papers that focus primarily on one issue affecting teaching on-line (student collaboration/problem solving, e-mail, gender issues, learning styles, teaching strategies, models for on-line courses, and institutional issues); and (2) general studies, which are broader in scope and typically address either broad or multiple issues involved in teaching on-line. The general category is subdivided by research type (general or multiple issues, case studies, and content analysis/historical studies). Within each section, studies are sorted by the primary author's last name. Bibliographic information is followed by the World Wide Web address of any full-text version of the study, key words, a classification of the type of research, and a short description of the paper. (SM)