Since 1999, MIT has undertaken an extensive effort in creating and implementing educational technology. Broadly speaking, there have been two kinds of efforts: developing web-based services for higher education and creating educational technology applications for use in the classroom. This article reviews a group of projects that produced educational technology applications for use in the classroom or for classroom-based activities and were assessed by educational researchers in the Teaching and Learning Laboratory (TLL). From those in depth studies, as well as less extensive involvement with a half dozen more initiatives, we draw three major findings on the role and impact of educational technologies as they were developed and used at MIT over 6 years: (1) the most successful educational technologies meet a specific instructional need that has been unmet or poorly met by traditional media; (2) too much technology or technology that does not work well can be detrimental; and (3) there are important relationships between the technologies and the learning environments in which they operate.