"Adapting to a Changing World" was commissioned by the National Science Foundation to examine the present status of undergraduate physics education, including the state of physics education research, and, most importantly, to develop a series of recommendations for improving physics education that draws from the knowledge we have about learning and effective teaching. Our committee has endeavored to do so, with great interest and more than a little passion. The Committee on Undergraduate Physics Education Research and Implementation was established in 2010 by the Board on Physics and Astronomy of the National Research Council. This report summarizes the committee's response to its statement of task, which requires the committee to produce a report that identifies the goals and challenges facing undergraduate physics education and identifies how best practices for undergraduate physics education can be implemented on a widespread and sustained basis, assess the status of physics education research (PER) and discuss how PER can assist in accomplishing the goal of improving undergraduate physics education best practices and education policy. The following are appended: (1) Statement of Task; (2) Meeting Agendas; (3) Biographies of Committee Members; and (4) Additional Suggested Reading Material. (Individual chapters contain references.) [This content was written by the Committee on Undergraduate Physics Education Research and Implementation; Board on Physics and Astronomy; Division on Engineering and Physical Sciences; National Research Council.]