William R. Miller is an American clinical psychologist and distinguished professor emeritus of psychology and psychiatry at the University of New Mexico. He is best known for his work on motivational interviewing (MI), a counseling approach he developed in the 1980s to facilitate behavioral change. Along with Stephen Rollnick, Miller has written extensively on MI, contributing to its widespread adoption in various health care and therapeutic settings. His research spans topics such as the treatment of addictive behaviors, the psychology of change, and the intersection of spirituality and psychology. Due to his significant contributions to clinical psychology, Miller has received numerous awards, including the Jellinek Memorial Award for his research on alcoholism.