Objective This study compared mental health service utilization by treatment modality and determined predictive factors of use among younger‐adult (18–35 years), middle‐aged adult (36–64 years), and older‐adult veterans (65+ years) with a newly recognized diagnosis of depression and/or anxiety disorder. Methods This retrospective study used data from the Veterans Health Administration National Patient Care Database outpatient and inpatient treatment files during the 2010 fiscal year (N = 583,692). Results Younger adults were the most likely to use mental health services, followed by middle‐aged adults and then older adults. Age was found to be one of the greatest predictors of utilization of mental health services, with odds of use being threefold among younger adults compared with older adults. Conclusions Continued efforts are needed to improve the awareness of, access to, and receipt of mental health services in veterans, particularly older adults, with depression and anxiety disorders. Published 2015. This article is a U.S. Government work and is in the public domain in the USA