This study attempted to identify the necessary and sufficient change factors in short-term anxiety-provoking psychotherapy (STAPP). Twenty patients were randomly assigned to either STAPP or a form of nondirective therapy almost devoid of psychodynamic elements but with common factors of psychotherapy intact. Both treatments were 20 sessions long, were manualized, and therapists in both conditions were experienced clinicians receiving manual-guided supervision. Most patients had a diagnosis of anxiety. Results showed that patients in both treatments improved greatly symptomatically and that no further gains were made after termination. Treatments were equally effective. The therapeutic alliance was a strong predictor of symptom improvement. The findings underscore the importance of common factors pertaining to the therapeutic relationship, and they may open to question, to some degree, the therapeutic effectiveness of psychodynamic technique factors in STAPP. The way in which specific and common factors can be brought together under the umbrella of the concept of affect attunement is discussed.