Objective sleep measures derived from a computerized movement detector attached to the child's leg, were obtained for a group of 31 toddlers (mean age: 18.5 months). The monitored sleep parameters were compared with maternal assessment of the child's sleep and her perception of his temperament. The validity of maternal diaries as a measure of the child's sleep was not supported. Nevertheless, a link between both subjective and objective sleep measures with temperament dimensions was indicated. The modest association between sleep and temperament may suggest either a continuity between some aspects of day- and night-time functioning or, alternatively, the influence of the child's sleep behavior in shaping the mother's perceptions of her toddler's temperament.