[Archived] Aggression in Young Children Services Proven to be Effective in Reducing Aggression

University of Washington, USA
, Rev. ed.

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Childhood aggression is escalating — and at younger ages.1 The developmental progression of aggression in children suggests that the propensity for physical aggression and oppositional behaviour is at its highest at age two.2 Typically, as children develop, aggression begins to subside in each subsequent year and reaches a relatively low level prior to entering school (ages five to six). However, for some young children, levels of aggressive behaviour remain high and eventually result in the diagnosis of Oppositional Defiant Disorder (ODD) or early onset Conduct Disorder (CD). These labels refer to an aggregate of disruptive and antisocial behaviours that include high rates of oppositionality, defiance, and aggression. Studies indicate that between 7% and 20% of children meet the diagnostic criteria for ODD and/or CD and that these rates may be as high as 35% for children from low-income welfare-dependent families.3


Research on the prevention and treatment of aggression is vitally important because the emergence of early onset ODD/CD in preschool children is stable over time and appears to be the single most important behavioural risk factor predictive of antisocial behaviour for boys and girls in adolescence.4,5In particular, physically aggressive behaviour in children as young as age three has repeatedly been found to predict the development of violent juvenile delinquency and drug abuse in adolescence,6 as well as depression and school dropout rates.7 There is some suggestion that, in the absence of intervention, early starter aggressive tendencies in children may crystallize around age eight.8 At this point in life, learning and behavioural problems may become less amenable to intervention and more likely to develop into a chronic disorder.9 Since treatment of aggression becomes increasingly difficult and more costly as children grow older, it seems both pragmatic and cost effective to offer treatment and prevention efforts during the toddler and preschool years. Unfortunately, recent projections suggest that less than 10% of school-aged children (and even fewer preschool-aged children) who need services for aggressive behaviour actually receive them;10 and less than half of this group receive empirically validated interventions.11


Family, parent, teacher/school, and child risk factors have all been associated with the development of conduct problems in young children. Low income, low education, high family stress, single parenthood, marital discord, maternal depression, and parental drug abuse are all factors that place children at particularly high risk of developing aggressive behaviour problems. Inconsistent, critical, abusive, and disengaged parenting or teaching behaviours are also important risk factors for the development and maintenance of children’s aggressive behaviours at home and in the classroom. Children who are temperamentally more impulsive, inattentive, and hyperactive often receive less encouragement and support and more punishment from parents and teachers. They also experience more peer rejection and social isolation at school. Such responses from adults and peers increase children’s risk of developing escalating aggression. Unfortunately, the risk of ongoing aggression and conduct problems seems to increase exponentially with children’s exposure to each additional risk factor.12

Research Context

Research has begun to evaluate treatments designed to reduce and prevent the ongoing development of aggression and to promote social and emotional competence in young children. Such efforts may also be seen as strategies to prevent the emergence of delinquency, substance abuse, and violence in later years. These treatments have targeted various constellations of the risk factors outlined above. Parent training programs, which represent the largest body of research evidence, have been designed to help counteract the parent and family risk factors by teaching parents positive and non-violent discipline strategies and supportive parenting approaches that promote social and emotional competence and reduce aggressive behaviours. A second treatment approach has been child-focused interventions designed to directly enhance children’s social, emotional, and cognitive competence by teaching appropriate social skills, effective problem solving, anger management, and emotional language. A third approach has consisted in training teachers to implement effective classroom management strategies so that they can reduce aggression in the classroom and strengthen social, emotional and academic competencies.  

Although many interventions that target these risk factors exist, relatively few well-designed, randomized control group treatment studies have been conducted with children under six who present with aggressive behaviour problems (ODD/CD). Moreover, it is difficult to find evaluations of parent, child, or teacher treatments for young children that have targeted reduction of aggression (the risk factor known to be related to later delinquency) as their primary outcome criteria. Recently, more multimodal treatments that link child, parent, teacher and child or classroom-based training interventions have emerged and several studies have suggested that targeting two or more risk factors leads to more sustained outcomes for children.13,14 

Key Research Questions

Given the large number of young children with aggressive and delinquent behaviour problems, is it important to evaluate the most efficient, effective, and cost-effective treatments? For whom do parent, child, or classroom interventions work to reduce aggression and promote social competence and under what conditions? Are all of these approaches needed or will one be sufficient at this age? What are the long-term effects of these treatments? Are there any child, family, or school-based risk factors that moderate the outcome of these interventions?

Recent Research Results

There are markedly fewer treatment studies conducted with preschool children diagnosed with ODD/CD than with school-aged children. The evaluations that have been conducted suggest that parental training is the single most effective treatment for reducing aggression in young children (ages two to five). Approximately 2/3 of children with ODD/CD can be brought into the normal range for aggression and social competence on standardized measures with results that are maintained one to four years later. Randomized control group studies have shown significant results in four parent programs: Parent–Child Interaction Therapy,15 Cope,16 Incredible Years,17 and Helping the Noncompliant Child.18 With regard to child social skills, emotional regulation and problem-solving treatments, only two control-group studies within this age group reduced aggression and/or promoted social and emotional competence in children diagnosed with conduct problems (i.e., Incredible Years’ Dinosaur Curriculum).13,14,19,20 Thus, child training shows promise, but more studies are needed. Three teacher-training programs that produced a reduction in classroom peer aggression compared with control classrooms. These programs include CLASS,21 PASS,22 and Incredible Years Teacher Training program.23,24 Other teacher-training programs with school-aged children (aged six to 12) have indicated significant improvements in aggressive behaviour (e.g., ref. 25).


The preschool years appear to be a crucial period for either the reduction or the crystallization of aggression. Unfortunately, the majority of intervention programs for aggression are introduced during the school-age and adolescent periods. These programs come too late in the developmental process of aggression. Indeed, because the socialization of aggression takes place during the preschool years, one would expect such programs to have their greatest impact on children during that period. The empirically validated treatments for preschool children with the aggressive behaviour problems mentioned above suggest that by working with parents, teachers, and children themselves, social and emotional competence can be enhanced and early onset aggression can be reduced significantly with sustainable results. Thus, by intervening early, the trajectory of early conduct problems leading to adolescent delinquency and adult antisocial behaviour may be corrected.


To this end, the following provisions should be made:


  • Invest in empirically validated parent training interventions that have been shown to reduce aggression in young children before age six. Make these available to high-risk populations and parents whose children present with aggressive behaviour problems.
  • Ensure that every child in daycare or preschool has a teacher or daycare provider who is trained in research-substantiated classroom management strategies and relationship skills.
  • For low-income children in preschool or daycare, focus on empirically validated classroom-based interventions designed to strengthen the social and emotional skills.
  • For high-risk children with aggressive behaviour problems, pay attention to empirically validated interventions that target multiple risk factors, including parents, teachers and children.


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How to cite this article:

Webster-Stratton C. [Archived] Aggression in Young Children Services Proven to be Effective in Reducing Aggression. In: Tremblay RE, Boivin M, Peters RDeV, eds. Tremblay RE, topic ed. Encyclopedia on Early Childhood Development [online]. https://www.child-encyclopedia.com/aggression/according-experts/aggression-young-children-services-proven-be-effective-reducing. Updated: September 2005. Accessed May 29, 2024.

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