Portfolios provide a means to represent excellence and variety in the work of one preparing to be a teacher. This paper reviews the implementation of portfolios with preservice teachers and describes appropriate electronic artifacts for inclusion in an electronic portfolio. Teaching portfolios are typically composed of artifacts, reproductions, productions, and attestations. Electronic portfolios can contain video, dialogues, simulations, links to references, and the interchanges of ideas in a chat room; they can be organized to be accessible in a searchable form; and they are useful in parallel problem solving. Portfolios can be used for student evaluation of personal learning, for program evaluation by showing the development of learners through their products to a team of evaluators, and for making archives for future generations of learners to build on. An electronic group portfolio developed by preservice teachers promotes reflection and discussion about what should be included, thus teaching cooperative activity and increasing social skills in a new medium. Group portfolios promote synergy and peer review, are a teaching device for both peer and teacher instruction, and support student choice. They are particularly appropriate for case studies, problem-based learning, and team teaching. Portfolio design is discussed, and techniques for capturing material electronically are presented. Links to web sites containing examples and references are interspersed throughout this document. (TD)