ABSTRACT Post-Traumatic Stress Disorder (PTSD), depression, and insomnia are prevalent among United States (US) military veterans. This study investigates whether Brain Boosters, a new cognitive enhancement group therapy, improves symptoms of PTSD, depression, and insomnia among veterans completing the groups. The study population includes 64 US military veterans treated in the setting of the Veterans Affairs (VA) Health Care System in Phoenix, AZ. Group members were US military veterans, age 22 to 87 (mean age=53.47), who had served in or after World War II (WWII), who sought mental health care at the Phoenix VA from 2007 through 2011. Participants were treated with Brain Boosters therapy. They completed measures of mental-health related symptoms before and after this therapy. Participants were assessed pre and post group with the PTSD Checklist for military personnel (PCL-M), the Patient Health Questionnaire (PHQ-9; a measure of depression symptoms), and the Insomnia Severity Index (ISI). Statistical analyses were done with paired samples t-tests and McNemar's tests, using SPSS. The hypotheses were that symptoms of PTSD, depression, and insomnia would show statistically significant improvement with Brain Boosters therapy. Results supported the hypotheses that symptoms of PTSD and depression would improve significantly. Insomnia did not show significant improvement. The results showed the mean PCL-M score was 54.84 before Brain Boosters therapy and 51.35 after (p= 0.008). The mean PHQ-9 score was 15.21 before Brain Boosters therapy and 13.05 after (p= 0.002). The mean ISI score was 15.98 before Brain Boosters Therapy and 14.46 after (p= 0.056). Although this is a nonrandom, uncontrolled trial, findings nevertheless suggest that Brain Boosters may be an effective therapy to reduce PTSD symptom severity and depression symptom severity. This may be especially important for veterans seeking alternatives to pharmacological intervention or traditional therapeutic interventions.