A 4-week training program for the personnel of two federally supported child day-care centers in Tucson had behavior modification of teacher aides as its objective. It was felt that by their mere presence in the classroom, the aides had an effect on the children and should thus be trained in appropriate behavior patterns and reinforcement techniques. A total of 14 aides--seven Negro, five Mexican-American, and two Anglo--from poverty backgrounds were divided into five groups, each headed by a teacher. Training procedures included group discussion of appropriate behaviors, demonstrations by teachers, practice with children, and immediate corrective feedback from the group leader. The aides were taught to observe and record a child's behavior and to give a positive response to good behavior, rather than a threatening response to disruptive behavior. Evaluation by means of video tapes, behavior rating scales, a behavioral task, and attitude tests showed a change in the aides. Prior to the program they had agreed on the theoretical desirability of reinforcing good behavior, but had not practiced this method. After training, there was a definite increase in reinforcement behaviors. (RT)