His research interests include the role of interpersonal skills in social support and cognitive/emotional factors in adjustment to chronic illness, specifically arthritis. He is also interested in the development of scales to measure health-related variables. Dr. DeVellis retired from full-time work with the Department of Health Behavior in 2012, but has remained active; the fourth edition of his highly-cited text, "Scale Development: Theory and Applications," is in press and will be published by Sage in 2017.