The current study marks the first randomized controlled trial to test the benefit of combining Seeking Safety (SS), a present-focused cognitive-behavioral therapy for co-occurring posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD), with sertraline, a front-line medication for PTSD shown to also impact drinking outcomes. Sixty-nine participants (81% female; 59% African American) with primarily childhood sexual (46%) and physical (39%) trauma exposure, and drug dependence in addition to AUD were randomized to receive a partial-dose (12 sessions) of SS with either sertraline (n = 32; M = 7 sessions) or placebo (n = 37; M = 6 sessions). Assessments conducted at baseline, end-of-treatment, 6- and 12-months posttreatment measured PTSD and AUD symptom severity. Both groups demonstrated significant improvement in PTSD symptoms. The SS plus sertraline group exhibited a significantly greater reduction in PTSD symptoms than the SS plus placebo group at end-of-treatment (M difference = -16.15, p = .04, d = 0.83), which was sustained at 6- and 12-month follow-up (M difference = -13.81, p = .04, d = 0.71, and M difference = -12.72, p = .05, d = 0.65, respectively). Both SS groups improved significantly on AUD severity at all posttreatment time points with no significant differences between SS plus sertraline and SS plus placebo. Results support the combining of a cognitive-behavioral therapy and sertraline for PTSD/AUD. Clinically significant reductions in both PTSD and AUD severity were achieved and sustained through 12-months follow-up, Moreover, greater mean improvement in PTSD symptoms was observed across all follow-up assessments in the SS plus sertraline group. (PsycINFO Database Record