Issues on usability, security, and mobility have always been the main concerns for e-commerce implementations that aim to gain widespread public acceptance. Smart Card Agent Environment is designed to address these issues by using a combination of software agent and smart card technology. In this chapter, a functional overview of the proposed environment is presented to illustrate how these two technologies can be integrated to offer e-commerce services with high usability, security, and mobility. To further demonstrate the concept, a prototype implementation of the environment has been carried out. In this implementation, an on-card agent residing in the smart card is capable of storing critical data securely, providing digital ID and signature, and carrying out user authentication. On the other hand, off-card agent would provide various high-level agent services that can be used to carry out e-commerce activities. Before the end of the chapter, practical considerations for issues on security, technology acceptance, infrastructure availability, and standardization will be discussed.