The PhD in computer science is, above all, a high-quality degree that is not conferred simply for the successful completion of a specified number of courses or years of study. It is a degree reserved for students who demonstrate a comprehensive understanding of computer science and an ability to do creative research. Each PhD student produces a significant piece of original research, presented in a written dissertation and defended in an oral examination. The doctor of philosophy in computer science is above all a degree of quality that is not conferred simply for the successful completion of a specified number of courses or years of study. It is a degree reserved for students who demonstrate both a comprehensive understanding of computer science and an ability to do creative research. Each Ph.D. student will produce a significant piece of original research, presented in a written dissertation and defended in an oral examination. The expected level of quality is such that one or more conference or journal articles could be based on the research described in the dissertation. Along the way students will likely generate several other research papers, many of them co-authored with their dissertation advisor and other graduate students. The structure of the Ph.D. program described here is intended to facilitate the process of learning how to do research. Throughout the program students will take courses intended to build a foundation of knowledge that is essential for advanced research. During their first year in the program, students begin with work on a directed research project under the close supervision of a faculty member. In the middle stages of the program, students will take fewer courses and spend most of their time building a foundation of knowledge in their research area and learning how to identify and solve open problems under the guidance of the Dissertation Advisory Committee (DAC). The final step is to propose an independent research topic, conduct the research, and then write and defend a dissertation.