A natural observational study was conducted to examine interactions between parents and their children in a suburban shopping mall, with a focus on the child's age and family composition. Three-hundred and eleven family groups that included at least a mother and one child (0 to 7 years old) were observed in a total of 13 sessions over 8 weekdays: mother and child dyads (n=155), mother, child, and father triads (n=54), mother, child, and grandparent triads/tetrads (n=24), mother, child, and other adult triads (n=27), and combinations of mother and child dyads (n=51). Regardless of the group composition, children were less likely to interact with other group members when they were older. In groups that included the father or either/both of the grandparents, mothers were less likely to interact with their children than other members were. Child carriers (e.g. a child sling, stroller, or shopping cart) were less likely to be used by mother, child, and father triads than by mother and child dyads, especially when the child was younger than one year old. This suggests that mothers use human and material resources in a complementary way. Groups that included infants younger than one year used their own stroller, while groups that included 1- to 3-year-old children used a shopping cart, although a stroller was used quite often by mother, child, and father triads even when the children were over 1 year old. One explanation for this is that as children become able to toddle around, a stroller would increasingly encumber the group‘s activities because a stroller cannot be left behind. However, parents in mother, child, and father triads could presumably react accordingly, with one pushing a stroller while the other carried the child in his/her arms. These findings reveal that mothers with preschool children may use human and material resources in accordance with different conditions and their child's age.