Lemur fulvus, L. catta, and L. variegatus differ markedly in the details of mother-infant relations. Do these differences account for those seen in adult life? We hope to determine this through interspecific cross-fostering. Here we describe the normal pattern of rearing of 5 infants among two groups of 2 and 5 adult L. variegatus, reared in the laboratory. The descriptions cover the first 7 months of life, and include the effects of maternal separation at 150 days of age, when estrus normally disrupts maternal care. The principal finding is that in the mother's absence young turn more to other adults than to their siblings, who are, apparently, not adequate social substitutes for adults.