Prior to this collaboration, he authored a number of CALL programs for teaching English in disc, CD-ROM, and web-based formats. He has published widely in the areas of CALL listening, teacher education, learner training, evaluation, standards, and theory, serves on the editorial boards of four major journals devoted to technology and language learning, and has been an invited speaker at a number of international conferences. He taught English to international students at UC San Diego, San Diego State, and Ohio University prior to coming to his current position at Stanford University.