As the primary goal of code review is to ensure that a change is free from defects, follows team conventions, solves a problem in a reasonable way, and is of high quality [6], we consider review feedback useful if it is judged useful by author of the change to enable him or her to meet these goals. We have observed that one of the top requests from teams using code review in their development process is a way to track the effectiveness of code review feedback and identify what they can do to improve effectiveness. As one team manager indicated, he’d like to know “was this an impactful review, a useful comment on the review? You know, not just a comment, but did it result in a change that wouldn’t have been there before.” The primary purpose of this paper is to address both challenges. Our objective is to identify the factors that impact the usefulness of code reviews, and to derive recommendations for effectiveness improvements.