The interactive effects of physiological reactivity and social support on children's memory were examined. Four- to 6-year-olds completed a laboratory protocol during which autonomic responses and salivary cortisol were measured. Memory was assessed shortly afterward and 2 weeks later. During the second interview, children were questioned by a supportive or nonsupportive interviewer. Few significant relations emerged between reactivity and children's short-term memory. Following a 2-week delay, cortisol reactivity was associated with poorer memory and autonomic reactivity was associated with increased accuracy among children questioned in a supportive manner but decreased accuracy among children questioned in a nonsupportive manner. Results question traditional conceptualizations of reactivity as a risk factor and instead suggest that reactivity may only confer risk in certain environmental contexts.