Under Part C of the Individuals with Disabilities Education Act (IDEA), children under the age of 3 are eligible for Early Intervention (EI) services: (1) if they have a developmental delay; or (2) if they have a diagnosed disability that is likely to result in a developmental delay. IDEA allows each state to define “developmental delay.” Therefore, what constitutes a developmental delay in one state may not be a developmental delay in another.
In Pennsylvania, a child has a developmental delay if he or she is 25% or more behind peers of the same age in at least one area or 1.5 standard deviations below the mean on appropriate standardized tests. (For example, a child who is 18 months old who is talking at the level of a 12 month old is more than 25% delayed in the area of communication and would be eligible for Early Intervention related to communication issues.)
New Jersey has a more stringent definition of developmental delay. In New Jersey, developmental delay is defined as a 25% delay in two or more developmental areas or a 33% delay in one area or a score of at least 2.0 standard deviations below the mean in one developmental area or 1.5 standard deviations below the mean in two or more of the developmental areas when evaluated with an appropriate standardized instrument.
In Delaware, a child is considered to have a developmental delay if he or she has a 25% delay in at least one area of development.