For Researchers

The Incredible Years® is a series of interlocking, comprehensive, and developmentally based programs targeting parents, teachers and children.

The Incredible Years® programs have been evaluated by the developer and independent investigators in the United States and other countries. Evaluations have included numerous randomized control group research studies using independent observations with diverse groups of parents and teachers. The programs have been found to be effective in strengthening teacher and parent management skills, improving children’s social and emotional competence and school readiness, and reducing behavior problems.

Theoretical Assumptions

For the past 33 years, Professor Emeritus Carolyn Webster-Stratton and her colleagues at the University of Washington’s Parenting Clinic have worked to develop and evaluate parent, teacher and child training programs for families with children with conduct problems and ADHD. She has also evaluated prevention versions of the parent, teacher and child programs with high risk families.

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Gerald R. Patterson’s theoretical work on childhood aggression strongly influenced the development of the training programs. Patterson’s social learning model emphasizes the importance of the family and teacher socialization processes, especially those affecting young children. His “coercion hypothesis” states that negative reinforcement develops and maintains children’s deviant behaviors and the parents’ and teachers’ critical or coercive behaviors. The parents’ or teachers’ behaviors must therefore be changed so that the children’s social interactions can be altered. If parents and teachers can learn to give more attention to positive behaviors than negative behaviors and manage children’s misbehavior with proactive discipline and appropriate problem-solving, the children can develop social competence, emotional regulation, and reduce aggressive behavior at home and at school.

Bandura’s modeling and self-efficacy theories form the basis for the training which is based on principles of live and video modeling, rehearsal, self-management, cognitive self-control, and self-reflection.

Bowlby’s attachment theory has elucidated the importance of the affective nature of the parent-child relationships. The foundation of the Incredible Years® programs focuses on building warm and nurturing parent-child and teacher-child relationships through child directed play, social and emotion coaching, praise and incentives.

Evidence of Effectiveness

The Incredible Years® program was selected as a model “Strengthening Families” program by the Center for Substance Abuse Prevention (CSAP), as an “exemplary” program by the Office of Juvenile Justice Delinquency Prevention (OJJDP), and as a “Blueprints” program by OJJDP. The Incredible Years® program series have also been recommended by the Home Office in the United Kingdom as one of the evidenced-based interventions for antisocial behavior and by Sure Start as a recommended program for families with children under five years. As such, the series has been subject to quality reviews by independent groups of scientists, evidenced excellent effectiveness in multiple randomized control group studies, and attained high overall consumer satisfaction ratings.

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Parent Program Evidence: Evidence of Parent Program Effectiveness as a Treatment Program with Clinic Populations of Children Diagnosed with Oppositional Defiant Disorder and ADHD (ages 3-8 years):

Eight randomized control group trials (RCTs) by the developer and six RCTs by independent investigators of the parenting series with diagnosed children have indicated the following significant findings:

  • Increases in positive parenting including child-directed play, coaching and praise and reduced use of criticism and negative commands.
  • Increases in parent use of effective limit-setting by replacing spanking/hitting and harsh discipline with proactive discipline techniques and increased monitoring.
  • Reductions in parental depression and increases in parental self-confidence.
  • Increases in positive family communication and problem-solving.
  • Reductions in conduct problems in children’s interactions with parents and increases in children’s positive affect and compliance to parental commands.
  • 2/3 of children in normal range at 3-year and at 10-year follow-up.
Evidence of Parent Program Effectiveness as a Prevention Program with a Selective Population of Socioeconomically Disadvantaged Families of Children (ages 2-12 years):

Four RCTs by the developer and six RCTs by independent investigators of the parenting series with high risk populations (e.g. Head Start and Sure Start) indicated significant improvements in positive parenting interactions, reductions in harsh discipline with children, reductions in aggressive behavior problems and increases in child social competence.

Teacher Program Evidence: Evidence of Teacher Classroom Management Program Effectiveness by Developer with Clinic Populations of Children Diagnosed with Oppositional Defiant Disorder (ages 3-8 years):

One RCT by the developer of the teacher training with diagnosed children indicated significant:

  • Increases in teacher use of praise and encouragement and reduced use of criticism and harsh discipline.
  • Increases in children’s positive affect and cooperation with teachers, positive interactions with peers, school readiness and engagement with school activities.
  • Reductions in peer aggression in the classroom.
Evidence of Teacher Classroom Management Program Effectiveness by Developer and Independent Investigators with Selected Populations of Socioeconomically Disadvantaged Children (ages 3-8 years):

Two RCTs by the developer and five RCTs by independent investigators of the teacher training series with high risk populations indicated significant improvements in positive discipline and proactive management skills and decreases in classroom aggression and increases in children’s pro social behavior.

Child Program Evidence: Evidence of Child Dinosaur Treatment Program Effectiveness by Developer and Independent Investigators with Clinic Populations of Children Diagnosed with Oppositional Defiant Disorder and ADHD (ages 4-8 years):

Three RCTs by the developer and one RCT by an independent investigator of the small group dinosaur child treatment series with diagnosed children indicated significant:

  • Increases in children’s emotional language, social skills, and appropriate cognitive problem-solving strategies with peers.
  • Reductions in conduct problems at home and school.
  • Reductions in hyperactivity and inattention.
Evidence of Child Dinosaur Classroom Program by Developer with Selected Populations of Socioeconomically Disadvantaged Populations (ages 3-8 years):

Two RCTs with Head Start families and Primary grade classrooms indicated significant improvements in school readiness, emotional regulation and social skills and reductions in behavior problems in the classroom. Summaries of this research can be found in the following two review chapters.

Read the Article (A Multifaceted Treatment Approach for Young Children) Read the Article (A School-Family Partnership)
View the comparative graphs (pdf)

Five Steps to Fidelity of Implementation

Identification and selection of the Incredible Years®, an “evidence-based,” “empirically validated,” or “best practices” mental health program is only the first step in service delivery.  To obtain similar results to those published, attention must be given to supervising the quality of the implementation of the program.

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The Incredible Years® Parent, Teacher, and Child Training Programs have been proven in numerous randomized control group studies to be effective for promoting positive parent and teacher interactions and relationships with children, strengthening children’s emotional literacy and self regulation, social competence and problem solving skills, and reducing behavior problems in both prevention and clinic populations.

To obtain similar outcomes it is important to assure that the program is delivered with the highest degree of fidelity possible. Fidelity means that the program is delivered in its entirety, using all the recommended components, therapeutic processes and number of sessions.

Our core training methods and supervision ensure replication of the Incredible Years® programs with fidelity. We offer five steps to success:

  1. standardized and comprehensive intervention materials (manual, books, DVDs)
  2. standardized training workshops for clinicians by certified mentors and trainers
  3. ongoing supervision, coaching and mentoring support
  4. fidelity monitoring
  5. agency organizational support
View the description of training methods and supervision

Information for Grants Agencies

If you are planning to use any of the Incredible Years® programs as part of a research grant we strongly recommend your leaders become certified as group leaders and that one of our certified trainers is involved in training your staff and providing ongoing consultation. We ask that you let us know about research projects and send us copies of the research results.

Read more about program implementation

Research Presentations

Please see the PDFs below for various research presentations that have been given regarding Incredible Years®

Presentations from 2021/2022 Online Mentor Meetings

IY Autism Programs in New Zealand - Impact Evaluation
Incredible Years Dissemination In Rhode Island: An Ecological Approach to Prevention and Early Intervention
IY In Los Angeles During The Pandemic And Small Group Dina Online Implementation
IY TCM & NEPS - Promoting Teacher Well Being, Self-Efficacy and Reducing Stress in Ireland
Reflections on the Cultural Benefits of Live Video Accreditation Reviews
The Changing Lives Initiative - Results Of Outcomes Evaluation
The PIRM Study In Norway - Supported Parenting Intervention For Families With Refugee Background
Transportation Of The Teacher Classroom Management Program to the Real World in Portugal
Transition To Primary School Of Children In Economic Disadvantage: Does Teacher Training Make A Difference
+Presentations from Previous Mentor Meetings

Presentations from the 2019 Mentor Meeting in Bainbridge Island, Washington

Incredible Years Mentor Meeting 2019 - Tailorining Incredible Years
Building Sustainable Implementations, By Dr Caroline White
Implementation Support And Scale Of The Incredible Years® In Colorado
Implementing The Incredible Years® In The West Bank
Incredible Years® Through A Māori Lens
Incredible Years® Training As A University Course
Incredible Years® Implementataion In Los Angeles County
Promoting Filipino Parent Enrollment In Incredible Years® Using Culturally Tailored Video

Presentations from the 2018 Mentor Meeting in Forcalquier, France

Incredible Years Mentor Meeting 2018 - Tailoring IY To Fit
Attachment Security In Children With Conduct Problems
Evaluation Of The IY-TCM Program In Norway
Implementation Of The IY Dinosaur School Program For At-Risk Students
Incredible Beginnings - Brinnington Trial And Evaluation
Incredible Beginnings In Dorset, UK - Supporting Children's Early Development
Ten Years Of The Ministry Of Parenting - Our Incredible Years Story


Presentations from the 2017 Mentor Meeting in Bainbridge Island, WA, USA

Incredible Years Mentor Meeting Seattle 2017: Promoting Connections
An RCT Of TCM In Portuguese Pre-schools: Effectiveness on teacher practices and child behavior
Giving hope to vulnerable families: Home coaching to address conduct problems
The Incredible Years Māori workforce in New Zealand
IY Toddler, Autism and Foster Carer trials in Wales
New Zealand IY Teacher Classroom Management Booster Sessions for Teachers: Sustainability of the IY Teacher Practice

Presentations from the 2016 Mentor Meeting in Utrecht, The Netherlands

Bandura revisited: Why coaching is so essential
Fathers' involvement in IY groups: Recruitment barriers and strategies to reduce them
For Whom Does IY Work And Why Joyce Weeland
IY Meta-analysis: Might the Incredible Years reduce Social Inequalities?
Meta-analytic Review Of IYPT And Parent Training For Formerly Incarcerated Mothers
Parenting Interventions for Disruptive Child Behavior: Transportability and Effective Components
The influence of therapist factors on the effectiveness of the IY parent program
Walter Matthys Clinical reflections IY Mentor Meeting 2016

Other Presentations

Birmingham Presentation, Mentor Meeting 2013
Teacher Classroom Management pilot in Wales
Portuguese Study Presentation at 2014 IY Mentor Meeting