ABSTRACT
The era in which Hans Eysenck (1952) concluded that psychotherapy was an insignificant influence on client functioning is long past. The last fifty years of rigorous research into psychotherapy efficacy and effectiveness have unequivocally demonstrated that therapy can be a powerful intervention for meaningful and long-lasting change in both the symptoms of psychological distress and general life satisfaction (for example, Lambert & Ogles, 2004; Seligman, 1995). Unfortunately, the evidence also unmistakably shows that psychotherapy produces significant deterioration effects in as many as 5 to 10% of those who seek it (Lambert & Ogles).
