Evolution continues to play an ever-increasing role in software engineering. Although changing a program is the core of software evolution, program change patterns have not been considered as a first class entity in most classic studies of software evolution. Past empirical studies of software evolution primarily relied on quantitative and statistical analyses of a programover time [1], but did not focus on semantic and qualitative change patterns of a program. We hypothesize that by treating change patterns as first class entities we can better understand software evolution and also aid programmers in changing software.