Even though early treatment of congenital hypothyroidism (CH) with newborn screening prevents the mental retardation previously seen in cretinism, affected children still exhibit subtle persisting neurocognitive deficits. One of their commonest problems is poor attention, which reflects both early disease severity and later (high) circulating thyroid hormone levels. While attention is currently regarded as multicomponential in nature, with different processing components supported by different brain regions, the specific components of attention affected by CH have not been identified. In light of animal evidence showing that neonatal thyroid hormone deficiencies impede the neurodevelopment of structures important for selective aspects of attention, we proposed a multicomponential approach to study attention in children with CH. This was accomplished via retrospective analysis of existing data on adolescents with CH whose attention was previously evaluated using multiple tests. Results showed significantly poorer overall attention in CH than controls with differences occurring mainly on focus and inhibit indices. However, performance on various indices was associated with different disease parameters. Poor encode and focus were correlated with more severe hypothyroidism and a longer period of thyroid hormone insufficiency and poor select and shift with higher thyroid hormone levels at testing. These results signify that thyroid hormone is important for the development and later regulation of brain structures supporting distinct aspects of attention. (JINS, 2001, 7, 734–744.)