What is the Gesell Developmental Observation?

What is the GDO-R?

The Gesell Developmental Observation-Revised (GDO-R) is a comprehensive multi-dimensional assessment system that assists educators, and other professionals in understanding characteristics of child behavior in relation to typical growth patterns between 2½ to 9 years of age.

The GDO-R uses direct observation to evaluate a child’s cognitive, language, motor and social-emotional responses in five strands (components): Developmental, Letter/Numbers, Language/Comprehension, Visual/Spatial and Social/Emotional/Adaptive.

The Results of the GDO-R 

A child’s performance on each strand (4 domains) corresponds to a strand Performance Level Rating, an overall Performance Level Rating and a Developmental Age.

Developmental Age is an identification in years and half-years that best describes a child’s behavior and performance on a developmental scale compared to most children. Developmental Age may be equal to, older or younger, than the child’s actual chronological age. 

The results also allow for an Overall Performance Level rating of Age Appropriate, Emerging or Concern. This information can be used as a guide to customize curricula and/or identify a child who may need additional diagnostic evaluation.

The components of the GDO-R assessment system include the GDO-R Examiner’s Manual, GDO-R Child Recording Form (CRF), GDO-R Examiner’s Script, TQ/PQ, manipulatives for various tasks, and an auto-calculating version of the GDO-R Strand Scoring Worksheet.  It is supported by current psychometric data published in the GDO-R Technical Report and meets the government mandates for initial screening of a child 3-6 years.

History of the GDO-R

The Gesell Developmental Schedules has also been known by GDS, the Gesell Maturity Scale, Yale Tests of Child Development, Gesell Preschool Test, Gesell Kindergarten Screener, and the Gesell Developmental Observation. The purpose of the original scale, developed by Dr. Arnold Gesell at Yale University, was to measure the development of infants and young children. Today, these tests no longer exist. The current assessment from the Gesell Program in Early Childhood is known as the Gesell Developmental Observation-Revised for ages 2 ½ to 9 years.

The Gesell Developmental Schedule was first published in 1925. The original scale was based on the normative data that was collected from a carefully conducted longitudinal study of early human development. The study focused on the various stages of development and how they unfolded over time.Throughout the years, it has been subjected to extensive research and has been subsequently refined and updated. The first revision was published in 1940. When Dr. Gesell retired from Yale in 1950, Yale retained ownership of the birth to age 3 schedules and Yale continued to refine them. The schedules for older children became the property of Gesell Program in Early Childhood, established in 1950. In 1964, 1965, 1972 and 1979, Dr. Francis Ilg and Dr. Louise Bates Ames, the founders of the Gesell Institute, refined, revised and collected data on children 5-10 years of age. The results were published in School Readiness; Behavior Tests used at the Gesell Institute. Once the leading infant intelligence measure from the 1930s through the 1960s, the Gesell Developmental Schedule was nothing short of a breakthrough in infant ability testing when it was first constructed- the first of its kind, actually. In 2011, the instrument was revised and data was collected only on ages 3-6 years. 

Get Trained to use the GDO-R

Gesell offers specialized GDO-R Workshops and ongoing technical assistance not available with most other assessment systems. Participants become qualified and valid examiners, reliable at determining a child’s Developmental Age and Performance Level Ratings across five strands.

When using the GDO-R, Gesell recommends using best practices during the assessment of very young children.

Gesell does not set policy or provide recommendations surrounding issues of retention, placement or readiness “scores” in association with the GDO-R.


"The Gesell seminar was very interesting and informative with many useful tools and supplies provided for step by step instructions throughout the material.  The hands-on exercises and student demonstrations were very helpful." - Phyllis from Dallas