The purpose of the present study was to learn how a mainstreamed mentally retarded or emotionally disturbed child is received in a regular classroom by the other pupils in the class. Each of 36 fifth grade boys interacted with one of three male confederates and 36 eighth grade boys interacted with one of three other male confederates. In each case the confederate was of the same age and grade as the subjects. He was presented to the subject as an ordinary child, as a mentally retarded child, or as an emotionally disturbed child who might soon attend their school and the subject was asked to estimate how the confederate would fit into the school. The confederate was always blind to condition and, after the interaction, the subject was questioned about the confederate by an experimenter also blind to condition. Behavioural measures taken from the sound recordings of the interaction showed that the subjects in the mentally retarded and emotionally disturbed conditions behaved in a less friendly and more anxious manner than in the control condition. They also wanted more social distance from the 'retarded' and the 'disturbed' confederate and expected their peers to be more rejecting toward them relative to the control condition. Essentially the same results were obtained for fifth and eighth grade boys and little difference was found between the two types of mental handicaps. The implication of the study for deinstitutionalization are discussed.