Fathers and mothers of firstborn infants completed parental responsibility surveys; recorded accessibility and direct interaction time in caregiving, play, and outings; and were videotaped in free-play with their infants at age 9 and 15 months. Fathers spent less time interacting with their infants than mothers and invested less time in accessibility, total interaction caregiving, play, and outings. Fathers and mothers interacted similarly with their infants during play. (Contains references.) (SM)