Abstract: | This study investigated the specificity of diagnostic classification in two standardized systems: DSM-IV and Diagnostic Classification: Zero to Three. A sample of 82 infants aged 1–24 months suffering from various psychogenic and functional pediatric symptoms was diagnosed applying both systems. For DC: 0–3 (the Diagnostic Classification on Mental Health and Developmental Disorders of Infancy and Early Childhood), this study presents results with respect to the specificity of symptom patterns. Twelve out of 27 symptoms, specific for disorders in early infancy, showed high specificity and were significantly discriminative for the diagnostic entities. These symptoms were differentiated for frequency and severity of occurrence for each diagnosis. In the sample, DSM-IV and DC: 0–3 diagnoses were compared. Additionally, 13 items of biographical-biological data were collected (e.g., low SES combined with very young or older mothers resulted in an increased risk for psychiatric disorders in early infancy). The data provide support for the idea that the use of DC: 0–3 in early infancy may be helpful in relation to daily routines and research by increasing the range of clearly defined diagnostic entities. |