The Department of Computer Science is one of the longest established computer science departments in the world and is consistently ranked as a top-5 graduate program. The department offers graduate work leading to a master's or doctoral degree, with an interdisciplinary master?s degree program in bioinformatics. In addition, the department offers an online professional master?s degree to reach students who are working full-time and unable to come to campus.

The home of the Department of Computer Science at Illinois is the Thomas M. Siebel Center for Computer Science, a state-of-the-art building that opened its doors in 2004. On the north side of campus, home to the College of Engineering, Siebel Center is an interactive computing habitat, made possible by a gift from alumnus Tom Siebel. The vision for the building was not only to create a magnificent space to work in, but to offer opportunities to investigate and apply computing tools on the building itself. Advanced wireless and wired communication networks, sensors, actuators, video capture and display equipment, video walls and information panels and storage and computing capabilities within the building allow researchers to examine communication and computation issues related to pervasive computing, multimedia infrastructure, building intelligence, security and privacy, and art.