In this information era, both business and living communities are truly IT driven and service oriented. As the globalization of the world economy accelerates with the fast advance of networking and computing technologies, IT plays a more and more critical role in assuring real-time collaborations for delivering needs across the world. Nowadays, world-class enterprises are eagerly embracing service-led business models aimed at creating highly profitable service-oriented businesses. They take advantage of their own years of experience and unique marketing, engineering, and application expertise and shift gears toward creating superior outcomes to best meet their customers’ needs in order to stay competitive. IT has been considered as one of the high-value services areas. In this chapter, the discussion will focus on IT as a service. We present IT development, research, and outsourcing as a knowledge service; on the other hand, we argue that IT as a service helps enterprises align their business operations, workforce, and technologies to maximize their profits by continuously improving their performance. Numerous research and development aspects of service-enterprise engineering from a business perspective will be briefly explored, and then computing methodologies and technologies to enable adaptive enterprise service computing in support of service-enterprise engineering will be simply studied and analyzed. Finally, future development and research avenues in this emerging interdisciplinary field will also be highlighted.