The study compared delay of treatment for posttraumatic stress disorder (PTSD), major depressive disorder, and alcohol use disorder among post-9/11 veterans versus pre-9/11 veterans and civilians. Methods: The 2012-2013 National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III), a nationally representative survey of U.S. noninstitutionalized adults, was used. Participants included 13,528 civilians, 1,130 pre-9/11 veterans, and 258 post-9/11 veterans with lifetime diagnoses of PTSD, major depression, or alcohol use disorder. Cox proportional hazard models, controlling for relevant demographic characteristics, were used to estimate differences in treatment delay (i.e., time between diagnosis and treatment). Results: Post-9/11 veterans were less likely to delay treatment for PTSD and depression than pre-9/11 veterans (adjusted hazard ratios [AHRs]=0.69 and 0.74, respectively) and civilians (AHRs=0.60 and 0.67, respectively). No differences in treatment delay were observed between post-9/11 veterans and pre-9/11 veterans or civilians for alcohol use disorder. In an exploratory analysis, post-9/11 veterans with past-year military health care coverage (e.g., Veterans Health Administration) had shorter delays for depression treatment compared with post-9/11 veterans without military coverage, pre-9/11 veterans regardless of health care coverage, and civilians, although past-year coverage did not predict treatment delay for PTSD or alcohol use disorder. Conclusions: Post-9/11 veterans were less likely to delay treatment for some common psychiatric conditions compared with pre-9/11 veterans or civilians, which may reflect efforts to engage recent veterans in mental health care. All groups exhibited low initiation of treatment for alcohol use disorder, highlighting the need for further engagement efforts.