Experimental and ethological studies were undertaken to clarify the role of positive and negative evaluations in the control of the child's performance on laboratory and classroom learning tasks. The results indicate that "social reinforcers" are effective to the extent that they communicate to the child unambiguous information on the adequacy of his performance. These events are normally of only modest effectiveness in the immediate control of performance as studied in both experimental and classroom settings. Negative statements, on the other hand, have been shown to be highly effective in both contexts. Further analysis suggests that the traditional focus upon social reinforcement processes oversimplifies the nature of the actual interpersonal controls used by the teacher. It is argued, in conclusion, that it is necessary to go beyond simple concepts of "social reinforcement" in order to come to grips with the interpersonal events that are effective in behavior development and behavior control. (Author/LAA)