To determine the contribution of infant temperament to the relationship between maternal sleep disturbance and depressive symptoms. Utilizing a repeated measures design, 112 couples recruited from childbirth education classes were assessed in third trimester and postpartum. Instruments included Center for Epidemiologic Studies Depression Scale, General Sleep Disturbance Scale, wrist actigraphy, and an investigator-developed tool to assess infant temperament completed by mothers and fathers. Regardless of infant temperament, mothers who slept < 4 h between midnight and 6 am and mothers who napped < 60 min during the day were at increased risk for depression at three months postpartum. Infant temperament was associated with maternal sleep but was not a significant predictor of depressive symptoms after controlling for other contextual factors. Postpartum clinical visits should include questions about maternal sleep so interventions can be directed toward sufficient sleep to minimize risk of postpartum depression.