In-service upgrading has been an accepted avenue for retraining practicing teachers in Singapore to keep abreast of changing curriculum requirements as well as infusion of information technology (IT) in teaching and learning. To cope with the teachers’ busy work schedules and many school commitments, upgrading courses were offered to the teachers primarily asynchronously, using the Internet platform with some integrated synchronous sessions. This chapter analyzes the rationale for the development of such a Web-based teacher-upgrading program and discusses the main issues of professional upgrading addressed in the development. Issues of adult learning in a learner-controlled adaptive learning environment and lifelong learning were addressed through an IT-infused asynchronous mode, providing the much-needed freedom in time management for the course participants. The development also includes delivery of high definition graphics through a customized hybrid system of CD-ROM and Web that addresses image-downloading bottleneck and thereby overcomes a basic problem of distance learning in geospatial education. Finally, reflections on the attending adult learners’ responses to such an upgrading program are discussed.