This study investigated discrepancies in partners' skills that arose during children's collaborative problem solving. Some researchers have concluded that expert peers' poor teaching skills seriously curtail the learning potential of expert-novice peer collaboration. This study examined the ways in which experts and novices negotiate and renegotiate their roles, and focused on the novices' behavior in role renegotiation. The hypothesis was that novices whose task skills increased would be more likely to renegotiate their role successfully than novices whose competence did not improve. Forty-eight kindergartners were identified from pretests in which children were asked to copy a Lego model. Expert-novice pairs were formed. Twelve novices were taught building and copying strategies by an adult after the first collaborative session, while the other 12 novices had individual practice sessions. Key comparisons involved changes in novices' roles from the first to the second collaborative session. Results showed that after the experimental manipulation, trained novices were more likely than untrained novices to renegotiate their role successfully. Contrary to expectations, trained novices did not use more sophisticated strategies. They were, however, more persistent in the frequency of their attempts and in the length of their negotiation sequences. (SH)