Two experiments examined six-month-olds' ability to form an abstract containment category. Results indicated that, after habituation to object pairs in a containment relation, infants looked reliably longer at an example of an unfamiliar versus familiar containment relation, indicating that they could form a categorical representation of containment. Findings also demonstrated that infants do not rely on object occlusion to discriminate containment from a support or a behind spatial relation. (Author/KB)