Inclusion Criteria:

In addition to the DSM-IV diagnostic criteria for major depressive disorder, the following conditions must be met for patient eligibility:

• Written informed consent.
• Subjects with a primary diagnosis of PD who also currently meet DSM-IV criteria for MDD
• Subjects must be stable on their anti-Parkinson treatment, as defined by no medication changes over the past 6 weeks
• Subjects may be taking an antidepressant as long as they have had a stable dose for up to 6 weeks and do not alter the dosage during the course of the study
• Men or women 40-80 years of age
• HAMD-17 scores > 14 at screen visit
• Score of 25 or greater on the Mini-Mental Status Examination
• Willing to come to MGH for screening and study participation

Exclusion Criteria:

Patients meeting any of the following criteria are to be excluded from the study:

• Subjects who, in the investigator's judgment, pose a current, serious suicidal or homicidal risk
• Patients who would not be appropriate for a delayed CBT control due to the severity of their depression based on clinical judgment as well as HAMD-17 scores > 28
• The following DSM-IV diagnoses: 1) substance use disorders, including alcohol dependence, active within the last 3 months; 2) schizophrenia; 3) delusional disorder; 4) psychotic disorders not elsewhere classified; 5) bipolar disorder; 6) MDD with psychotic features
• Subjects who meet DSM-IV criteria for dementia
• Severe, unstable concurrent medical conditions (determined by his/her physician) that are likely to require hospitalization within six months from study entry (e.g., a patient with severe congestive heart failure who has a history of recent hospital admissions)
• Subjects may not be receiving a psychosocial intervention that is specific for depression; psychosocial interventions not specific for depression (e.g., couples counseling) and established for three or more months before screen visit are allowed