Inclusion Criteria:

• Receiving treatment in an outpatient, residential, or in-patient setting
• Meets DSM-IV diagnostic criteria for at least one of the following disorders: anxiety disorder, depressive disorder, eating disorder, or obsessive-compulsive disorder
• English- or Spanish-speaking

Exclusion Criteria:

• Inpatient status IF the enrolling inpatient clinician will not continue to follow the patient for the duration of the study
• Sibling that is already enrolled in the study
• Imminently suicidal and unable to comply with a no-suicide contract or, in the opinion of the treating clinician, has inadequate family monitoring for suicidality
• Acutely psychotic at study entry
• A demonstrated lack of benefit from or intolerance to SSRI/SNRI antidepressants, as a class
• Receiving treatment with a tricyclic antidepressant (TCA) at study enrollment, with the exception of low doses for enuresis for chronic pain. Patients may receive adjunctive TCA treatment during the study at the clinician's discretion.
• Received a monoamine oxidase inhibitor (MAOI), such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate), within the past 30 days
• Parasuicidal behavior or milder forms of suicidality or activation that do not meet the diagnostic criteria
• Refusal to participate in the pharmacogenomic study
• For bipolar depressed patients, a mixed- or manic-state at study entry without stable treatment with a mood stabilizer for manic symptoms
• Patient or family is unable to comply with the protocol