Clinical Child and Family Psychology Review, Vol. 8, No. 4, December 2005 ( C  2005) DOI: 10.1007/s10567-005-8809-y The Role of Temperament in the Etiology of Child Psychopathology Peter Muris 1,3 and Thomas H. Ollendick 2 A substantial proportion of children and adolescents come to suffer from psychological dis- orders. This article focuses on the temperament factors that are involved in the pathogenesis of child psychopathology. It is argued that besides the reactive temperament factor of emo- tionality/neuroticism, the regulative process of effortful control also plays an important role in the etiology and maintenance of internalizing and externalizing problems in youths. More specifically, vulnerability to child psychopathology is determined by a temperament that is characterized by high levels of emotionality/neuroticism and low levels of effortful control. Models are hypothesized in which reactive and regulative temperament factors either have interactive or additive effects on the development of psychological disorders in children, and conceptualized in terms of a developmental psychopathology perspective. Directions for fu- ture research and clinical implications of this temperamental view on psychopathology are discussed. KEY WORDS: temperament; emotionality/neuroticism; effortful control; psychopathology; children and adolescents. Three children are referred to a clinical child psychologist. The parents of all three have divorced during the past year. Tim (9-years old) has become extremely anxious since that event. He does not dare to stay home alone anymore. When his mother wants to go out for shopping, Tim panics and begs her not to go. Going to bed at night is also a problem. His mother has great difficulties getting Tim upstairs to go to bed and when he is finally in bed, she has to stay with him until he falls asleep. Almost every night, Tim awakens in terror because of a nightmare, and after being calmed down he has problems falling asleep again. It is clear that Tim exhibits many char- acteristics of an anxiety disorder. Tony (11-years old) displays different symptoms. Since the divorce of his 1 Institute of Psychology, Erasmus University Rotterdam, The Netherlands. 2 Virginia Polytechnic and State University, United States of America. 3 Address all correspondence to Peter Muris, Professor, Institute of Psychology, Erasmus University Rotterdam, Burgemeester Oudlaan 50, Suite J5-31, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands; e-mail: muris@fsw.eur.nl. parents, he has become very quiet and increasingly retreats in his room. He seems unhappy and sad most of the time, and even things that used to bring him great joy do not seem to interest him anymore. At school, Tony shows a total lack of energy: his perfor- mance deteriorates and because of his aloof attitude, he becomes increasingly isolated from the other chil- dren. Obviously, Tony appears to suffer from a de- pressive disorder. And finally Trevor (10-years old), since his parents have divorced, has become very touchy and gets easily annoyed. He often argues with his parents, does not obey his teachers any more, and frequently fights with other students on the school- yard. Lately, he was caught while stealing candy in the local supermarket. Clearly, Trevor shows early signs of a disruptive behavior disorder. Tim, Tony, and Trevor: three children who have been confronted with the same negative life event and since then display different abnormal behavior. Two important questions can be raised in the con- text of this common clinical observation. The first question is why do these children develop psycho- logical problems after being exposed to a negative 271 1096-4037/05/1200-0271/0 C  2005 Springer Science+Business Media, Inc.