 The medication phase will last 12 weeks. Patients will receive standard TBI care during this period. Current standard of care for patients with moderate-severe TBI following a full evaluation with medicalsurgical treatment of any acute medicalsurgical conditions is approximately 8 weeks of Convalescent Leave Home CVL followed by a gradual return to duty. Mild TBI patients typically receive 1-4 weeks of CVL followed by a gradual return to duty. Civilians would have similar schedules for resumption of activities. From current referral patterns, we expect most patients to have moderate traumatic brain injuries. The DVHIP experience suggests that patients are virtually never referred to DVHIP severely depressed and already on therapeutic levels of antidepressants. More commonly, patients are referred with mild-moderate symptoms of sleep difficulties, headache, irritability andor depression. Because no randomized, controlled trials exist to suggest that current medical treatment is effective in these patients, and because a substantial placebo effect is a known reality, the design of this study randomization to sertraline or placebo is appropriate. Also, we have cared for a few patients who, although clinically depressed, refused medications. We worked with them in a supportive educational framework, and in some cases, their depressions remitted. Thus, the best treatment for these patients is far from established. It is likely that future research will help clarify which treatments are best for which patients. For this study, patients who may have been started on a tricyclic antidepressant e.g., for headache or an SSRI will be withdrawn from these medications for 10 days prior to the start of the study medication. Patients will be informed of concomitant medication options if the test article sertraline or placebo is not sufficient for treating their symptoms, or if they feel they need medication prior to the start of the test article. All patients will be contacted weekly during the medication phase to assess general condition, current symptoms, and assessment of compliance. Patients will be rated for improvement at weeks 3, 6, and 9 for possible medication adjustment. The determination of medication adjustment will be made by study personnel at Walter Reed only. If patients require a clinical medical appointment during the 12 weeks, patients will be seen at WRAMC if possible. If not possible, study personnel will be available to speak with the patients clinician at a local medical facility. Patients will return to WRAMC at 12 weeks for a follow-up evaluation of their symptoms, or they will be contacted by phone if unable to return to WRAMC for their 12 week evaluation. After the 12 week evaluation, patients will be tapered off sertraline or placebo over 2 weeks. Tapering and discontinuation of the study medication or placebo will be done on a gradual basis over the 2 weeks e.g., If the patient is on 150 mg, she could take 100 mg for 1 week, 50 mg for one week, then DC. If, following the 12 week evaluation, subjects have recurrent symptoms which are distressing to them, or believe they need medication to keep their symptoms from recurring, pharmacologic and nonpharmacologic treatments will be discussed with them. Patients will be offered appropriate treatment, including sertraline, if medically indicated. The blind will not yet be broken, that is, patients will not be able to learn if they were being treated with placebo or sertraline. Subjects will then be contacted by phone or seen at 3, 6, 9, and 12 months following their 12 week follow-up evaluation for an assessment of their symptoms and general level of functioning. If patients are in the area, these follow-up evaluation may be done in person. 