This study examined the effects of training and follow-up training on teacher aides' effectiveness in the reinforcement of reading skills and motivational techniques introduced by kindergarten and first-grade classroom teachers. The following questions were addressed: (1) are trained assistants rated as more effective than untrained assistants? (2) are trained assistants who participate in a single follow-up session rated as more effective than those with initial training only? and (3) are trained assistants who participate in a second follow-up session rated as more effective than those with only one follow-up session? Participants (N=66) were organized into 2 groups: 44 were enrolled in 40 hours of in-service training, with half selected randomly to participate in either 1 or 2 follow-up sessions; the other 22 served as a control group. Data were gathered utilizing classroom observations and video-taped lessons, with rankings completed by central office administrators. Results indicate that teacher assistants receiving training and follow-up in extending classroom instruction were more effective than those without training, and that those with follow-up training were rated as more effective than those without follow-up training. (LL)