Developmental Delay: A child from birth to 36 months of age will be considered to exhibit developmental delay when that child has not reached 50 per cent of the developmental milestones expected at his/her chronological age, in one or more of the following domains: Physical: fine and/or gross motor muscle development; sensory (vision and hearing) Cognitive: thinking, mental or problem-solving development Language/Communication: receiving information (receptive) and expressing understood information (expressive) development Social/Emotional: internal and external adaptation to environmental stimuli development Self-help: adaptive development to attain basic needs. Determination that a child is developmentally delayed will be based on professional evaluation, including informed clinical opinion, and will include parental involvement and input. Arizona's definition of "eligible child" does not include children who are at risk of having substantial delays if early intervention services are not provided.