Four experiments examined the effects of the number of features and feature relations on learning and long-term memory in infants. Three-month-olds learned to activate a mobile composed of either two or three kinds of blocks that differed in color, the figures displayed on them, and the figures' colors. Twenty-four hours later, infants trained with two objects discriminated feature recombinations but those trained with three objects did not. Even infants trained with three objects discriminated novel features, however, indicating that they remembered the individual features but not the relations among them. A subsequent experiment revealed that this dissociation between features and relations was induced by differential accessibility to memory rather than an encoding failure. We conclude that the size of the memory load selectively constrains infants' long-term memory for relational information. These results suggest that in infancy, as in adulthood, features and relations are psychologically distinct and that memory organization parallels the organization of perceptual processing.