DC:0–5™ Manual and Training

An essential guide to infant and early childhood mental health diagnostic formulation with infants, young children, and their families, in a wide range of settings.

We are proud to offer the DC:0–5™ Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood Version 2.0, the DC:0–5™ Casebook, and official DC:0–5™ Training.

DC:0-5™ Manual

In 1994, ZERO TO THREE published its groundbreaking manual, DC:0–3 Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood. The first developmentally based system for diagnosing mental health and developmental disorders in infants and toddlers, this critically important guide quickly became an indispensable resource for mental health clinicians, counselors, physicians, early interventionists, educators, and researchers.

DC:0–5™ Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood, first released in 2016, captures new findings relevant to diagnosis in young children and addresses unresolved issues in the field. The updated DC:0–5™ Version 2.0 arrived in 2021 and enhances the professional’s ability to diagnose and treat mental health problems in the earliest years by identifying and describing disorders not addressed in other classification systems and by pointing the way to effective intervention approaches.

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What's New in DC:0-5™?

DC:0–5™ Version 2.0 includes clarifying language throughout the manual and the inclusion of numerical codes to help facilitate the inclusion of DC:0-5 disorders.

Discrete numerical coding provides consistency among various disorder lists and can prevent misunderstanding when translating diagnoses into other languages. This updated information is available for free as a supplemental. 

  • Includes disorders occurring in children from birth through 5 years old
  • Criteria extended to younger ages when appropriate, including, in some cases, to the first year of life
  • Introduces discussion of several new disorders, including:
    • Relationship-Specific Disorder of Early Childhood
    • Dysregulated Anger and Aggression Disorder of Early Childhood
    • Atypical Social-Communication Emergent Neurodevelopmental Disorder
  • Retains the multi-axial system, allowing optimal consideration of context in assessment and diagnosis; most axes revised substantially

DC:0–5™ Infant Mental Health Training

DC:0–5™: Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood captures the latest scientific findings and clinical research on infant and early childhood mental health.

Contact us to learn more about infant mental health trainings and options for customized packages that meet your specific needs.  ZERO TO THREE is the only official source of training for DC:0–5.

  • The DC:0–5 Overview provides a foundational summary for professionals who work with infants and young children, available as a 90-minute webinar or 4-hour virtual or in-person infant mental health training event. The overview helps participants understand that infant and young children can experience mental health and developmental disorders, and consider their own role-specific response to this information. Participants will gain familiarity with the background, approach, and content areas of DC:0–5.
  • The DC:0–5 Clinical Training promotes an approach to diagnosis that centers culture and is developmentally sensitive and relationship-based. The infant mental health training focuses on the importance of using a developmentally sensitive, relationship-based, contextually grounded, and empirically supported system of diagnostic classification with children from birth through 5 years old.
  • The DC:0–5 Certified Training-of-Trainers (ToT) prepares clinicians to deliver the ZERO TO THREE DC:0–5 Training curriculum to clinicians from fields of mental health, health, and early intervention who are responsible for diagnosis in their own sites or locales. The ToT is available virtually or in-person. Clinicians who have successfully completed the DC:0–5 Clinical Training and who meet other eligibility criteria may apply to participate in the ToT and pursue ZERO TO THREE Trainer Certification. 
  • Community of Learners (CoL) events promote participants’ analysis, reflection, and exploration of applying content knowledge in their professional practice. Ninety-minute CoL events can be provided virtually or in-person as follow-up to the DC:0–5 Clinical Training. CoL participants’ learning is enhanced through collaborative dialogue with a focus on real-world application. 
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Interested in training for yourself? Browse our upcoming DC:0-5 individual registration events.


The New DC:0–5™ Casebook

Featuring over 15 case studies jam-packed with practical tips to support your work with young children and their families.

The casebook is a compilation of case studies as a companion volume to DC:0–5™: Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood (DC:0–5™; ZERO TO THREE, 2016, 2021). It is designed to strengthen understanding of clinical disorders in infancy and early childhood, and to help clinicians better understand the application of the multiaxial framework and culturally sensitive/relational approach to diagnosis that is fundamental to DC:0–5™.

Professional Development Resources

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