The current study examined the extent to which child sex and fear reactivity were linked to mothers’ observed use of supportive and intrusive parenting behaviors. Two dimensions of observed fear reactivity were considered: distress (i.e., fearfulness) and approach (i.e., fearlessness). The sample consisted of 160 predominantly African American, low-income families that included mothers, 1 sibling approximately 2 years old, and the closest age older sibling who was approximately 4 years old. Results from fixed-effects within-family models indicated that above and beyond the main effect of child engagement on observed parenting behaviors, child sex moderated associations between 2 dimensions of fear reactivity and mothers’ observed parenting. Specifically, mothers were observed to be less supportive during interactions with girls rated as high on fear approach and more intrusive during interactions with girls rated as high on fear distress. These patterns suggest that during early childhood, girls’ individual characteristics may be more closely linked to mothers’ parenting quality than are boys’ characteristics.