The aim of the study was to examine whether and how infant negative emotionality, depression in the caregiver, and marital emotional support are related to the caregiver's reactivity/sensitivity. The central question concerned interaction effects between these risk factors. Furthermore, it was of special, interest whether there were interaction effects of infant positive and negative emotionality on the reactivity/sensitivity of the caregiver. Participants were 101 mothers and their healthy 4-month-olds. The infant temperament characteristics were measured by parent report as well as in the laboratory. Caregiver behavior was observed during home visits. Hierarchical regression analyses were computed, Whereas there were no direct associations between either maternal depression or infant negative emotionality and maternal reactivity/sensitivity, the interaction of the two risk factors proved highly significant. Good marital support was directly linked to maternal reactivity/sensitivity. The relevance of positive infant emotionality could not be demonstrated. (C) 2000 Elsevier Science Inc. All rights reserved.