In view of conflicting claims about children's sensitivity to the needs of other children in learning situations, the present study was designed to explore the sensitivity of child and adult tutors in one-to-one tutoring interactions. Sixteen adults and 31 11- and 9-year-olds tutored 47 9-year-old tutees on an animal classification task. Tutors were tested on their ability to apply the rules and knowledge they had obtained after training, and tutees were tested after being tutored. On all the verbal and nonverbal tutoring indices adult tutors showed gyeater sensitivity than child tutors: they were more likely to display behaviours which promoted efficient learning in their tutees. Results suggested that tutors operated on the basis of an implicit theory of teaching which involves three types of sensitivity: (1) sensitivity to the learner's need to have sufficient information for understanding the task coupled with adequate checks on the learner's understanding; (2) sensitivity to the learner's need to participate actively in the learning process; and (3) sensitivity to differences in learning abilities among individual learners, and being able to accommodate to them.