The cataleptogenic effects of the selective dopamine D1 receptor antagonist, SCH 23390, increased between 13 and 17 days of age in male pups. Seventeen- and 21-day-old pups showed equivalent catalepsy. Scopolamine blocked SCH 23390-induced catalepsy in 21-day-old pups but had little effect in 13-day-old pups. The development and cholinergic sensitivity of SCH 23390-induced catalepsy are similar to those seen after D2 or mixed D1/D2 receptor blockade. Cholinergic maturation appears to be an important component in the development of adult-like catalepsy, and the nature of a D1-acetylcholine interaction mediating catalepsy remains to be determined.