Ascertaining the efficacy and effectiveness of psychotherapeutic interventions: An international review

Outcome studies of psychotherapy may be categorized into two broad strategi es: The efficiacy of interventions is determined with randomized controlled trials while the effectiveness is determined under clinical conditions. Bo th strategies and their differences are represented and discussed against t he background of results of psychotherapy process research. Difficulties to generalize about interventions that have been designed under laboratory an d artifical conditions are discussed and possible solutions for an integrat ion of these strategies as well as new trends in psychotherapy research are presented.