Panic disorder is characterized by unexpected panic attacks, anxiety about experiencing future attacks, and avoidance or dread of situations where attacks might occur. Panic disorder can be diagnosed either with or without the presence of agoraphobia. Cognitive-behavioral therapy (CBT) is an empirically supported intervention that American Psychiatric Association guidelines recommend with substantial clinical confidence for the treatment of panic disorder. Sessions begin with a brief review of material from the prior week, enabling the therapist to assess the client's perception and understanding of previously covered material. When treating panic disorder with CBT, therapists integrate their knowledge of available research, their clinical experience, and their understanding of a client's particular circumstances and characteristics when making clinical decisions. Decisions about how to implement a CBT technique, or whether to use it at all, can also be influenced by client characteristics and clinical expertise.