This treatment intervention trial is designed for men and women with either alcohol misuse (e.g. hazardous or binge drinking) or alcohol use disorders (alcohol abuse or dependence) and comorbid PTSD. Participants will be randomly assigned to one of two treatments (a cognitive behavioral treatment intervention called "Seeking Safety" + Medication ("Zoloft") or Seeking Safety + placebo) and will be evaluated at baseline, at completion of the treatment (12 sessions over 12 weeks), and again at 6 months and 12 months post-treatment.

The impetus for the current study is to contribute to the development of effective treatments targeted for men and women with either alcohol misuse (e.g., hazardous or binge drinking) or alcohol use disorders (e.g. alcohol abuse or alcohol dependence) and comorbid PTSD. Research findings have shown that these individuals have poorer treatment outcomes and show more severe symptoms than treatment seeking alcohol-misusing or alcohol dependent participants without PTSD. The aim of this study is to replicate and expand on 1) pilot studies demonstrating the effectiveness of a manualized cognitive-behavioral treatment specifically designed for individuals with comorbid substance use disorders and PTSD, "Seeking Safety" 2) preliminary results on the effectiveness of the antidepressant sertraline ("Zoloft") for a dually diagnosed population and 3) the examination of the effectiveness of these interventions over either treatment alone. We are comparing "Seeking Safety" alone to "Seeking Safety" in combination with the antidepressant medication sertraline ("Zoloft") in terms of their effectiveness in reducing alcohol use and PTSD symptoms. Participants will be randomly assigned to one of two treatments (Seeking Safety + Med or Seeking Safety + placebo) and will be evaluated at baseline, at completion of the treatment (12 sessions over 12 weeks), and again at 6 months and 12 months post-treatment. Secondary aims of the study include exploring potential differences between alcoholic subtypes on treatment outcomes; impact of combined treatment on treatment participation and global psychiatric symptoms; differences in the time course and order of changes in alcohol and drug use and PTSD symptoms by condition.

Inclusion Criteria:

1. Males and females who are a minimum of 18 years and maximum of 65 years.
2. Participants meet Diagnostic and Statistical Manual Diploma in Social Medicine IV (DSM-IV) criteria for current alcohol misuse, abuse or dependence.
3. Participants must have current alcohol use over past 90 days defined by more than or equal to 2 heavy drinking days or more than or equal to 14 drinks over 30 consecutive days or abstinence less than or equal to 21 consecutive days.
4. Participants meet criteria for full or subthreshold PTSD. Subthreshold PTSD criteria differs from full PTSD in that the individual meets cluster C (numbing) OR cluster D (hyperarousal) whereas full PTSD requires that the individual meets both cluster C and D.
5. Participants demonstrate no gross organic mental syndrome.
6. Participants are capable of giving informed consent and capable of complying with study procedures.
7. Participants speak English.

Exclusion Criteria:

1. Individuals who are at significant risk for suicide based on their current mental state or history.
2. Participants with other current Axis I psychiatric disorders that, in the investigators' judgment, are unstable and would be disrupted by study medications. Current diagnosis of Bipolar I and psychotic disorders are exclusionary.
3. Participants who are currently severely depressed.
4. Participants with a history of psychosis or mania.
5. Participants with organic mental syndrome.
6. Participants physiologically dependent on any substance other than alcohol (excluding nicotine or caffeine or medically stable and managed methadone).
7. Participants with comorbid substance abuse disorder who require detoxification treatment.
8. Participants with unstable or significant physical disorders (e.g., uncontrolled hypertension, poorly-controlled diabetes, alanine aminotransferase/aspartate aminotransaminase (AST/ALT) three times the upper limit of normal) that would increase the risk of study participation.
9. Participants with a known history of seizures (not related to alcohol withdrawal).
10. Participants with moderate to severe alcohol withdrawal that would require pharmacological intervention.
11. Participants currently taking prescribed psychotropic medication that is contraindicated for use with sertraline (e.g. antidepressant medications except for mirtazapine or trazodone when used for the treatment of insomnia ) and/or psychotropic medications where the participant has not achieved a stabilized regimen. Participants that are stable on medications that are not contraindicated with the use of sertraline (e.g., Methadone or Adderall) will not be excluded.
12. A history of an allergic reaction to sertraline.
13. Women who are currently pregnant or are trying to get pregnant or are nursing or are pre-menopausal and sexually active but not using effective birth control.
14. Participants refusing to be audio or videotaped.