A 90-point scale used assess the quality of an infant-parent ( or caretaker) relationship based on a continuum from well adapted to grossly impaired. It should be completed only after a thorough clinical evaluation of the infant's (0-5) problems. The relationship problems may stem from within the infant, within the caregiver(s), between the infant and the caregiver, or from the larger social environment. The PIR-GAS does not directly correlate to the C-GAS and GAF. Rather it is a supplement to the DC03 Axis II (personality disorder/mental retardation) diagnostic classification. DCO3 , Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood (0-5). The system is designed to help clinicians recognize individual differences in ways infants and young children relate to their primary care giver.

The scale evolved from work conducted by a task force of clinicians and through the National Center for Clinical Infant programs, Zero to Three. The group has developed a diagnostic framework using a systematic developmentally based approach to classification of mental health and developmental disabilities in a child's first five years of life.

The PIR-GAS is not a standard global assessment scale. It measures the relationship between the infant or toddler and its primary caretakers. These scale should be used to document level of functioning or relationship (in the case of the PIR-GAS) at the time of evaluation and at the end of treatment. Periodic interim assessments should be made for extended treatment.