Given that PTSD is among the most commonly comorbid diagnoses with substance use within veteran samples (e.g. Bonn-Miller et al., 2012), Fontana et al. (2012) reported a noteworthy exception to the prevailing viewpoint that dually diagnosed veterans evidence poorer treatment outcomes than veterans without co-occurring substance use and mental illness. Fontana et al. (2012) analyzed data collected from two samples of veteran patients (n=8,599) who participated in one of the 42 residential PTSD treatment programs included in the evaluation. Veterans diagnosed with both a substance use disorder and PTSD responded more positively to treatment, as indexed by greater reductions in PTSD symptomatology, than veterans with only a PTSD diagnosis. The inpatient nature of the treatment program may have contributed to these findings. Voluntary admission to an in-patient program would suggest that dually diagnosed veterans had likely already undergone a degree of pre-treatment change in addictive behavior, which is highly predictive of treatment success (Stasiewicz et al., 2013). Further, restricted access to substances and substance use triggers which heighten PTSD symptoms may have contributed to greater decreases in symptomatology than observed among veterans who had not abused substances, at least in the short-term. The authors conclude that PTSD and substance use may share a bi-directional relationship and that improvement in substance use symptoms alone may decrease PTSD symptomatology. Indeed, there is a precedence for such assertions as substance use treatment alone has been shown to reduce associated impairments across domains (e.g. Stuart et al., 2003).