Participants in this study will be screened with medical and psychiatric interviews, a physical examination, electrocardiogram (ECG), and blood tests. Participants will then be randomly assigned to receive either paroxetine plus clonazepam or paroxetine plus placebo (an inactive pill) for 12 weeks. Participants will have weekly clinic visits during which symptoms and drug side effects will be checked and an interview to evaluate panic disorder and depression symptoms will be conducted.