There is a high rate of comorbidity with alcohol dependence (AD) and post traumatic stress disorder (PTSD). The rates of PTSD among individuals with AD are at least twice as high as those in the general population. In addition, alcohol dependence is the most common comorbid condition in men with PTSD. Despite this, little is known about how to best treat individuals with comorbid AD and PTSD. The use of anticonvulsants represents a novel approach to treatment that may target symptoms of both AD and PTSD. Both Topiramate and Lamotrigine act on the GABAergic and glutamatergic systems. Topiramate has GABAergic effects by robustly increasing brain GABA, and antiglutamatergic effects by inhibiting glutamate function that might antagonize alcohol's rewarding effects in AD and could contribute to the regulating of reexperiencing and arousal symptoms in PTSD. Lamotrigine is a glutamate-inhibiting anticonvulsant that has shown efficacy in some dually diagnosed patients with alcohol dependence, and in patients with PTSD. Neither topiramate nor lamotrigine have been used to treat patients with comorbid PTSD and AD. Methods: Ninety men and women with a current diagnosis of AD and PTSD will be enrolled in a 16-week trial. They will be assigned, in a double-blind fashion, to either topiramate, lamotrigine or placebo. Significance: This project will be the first to compare anticonvulsants (topiramate and lamotrigine) to placebo as effective treatments for reducing alcohol consumption and PTSD symptoms in patients with AD and PTSD.