Children from preschools in Australia (AUST) were compared with indigenous children from preschools at Hanuabada and Kaugere in Papua New Guinea (PNG). The effects of modelling and instruction, separately and together, on their performance in problem‐solving tasks were evaluated. In addition, a within‐culture comparison was made of the two PNG groups. ANCOVAS were computed with the factors group (PNG‐AUST and Hanuabada‐Kaugere), treatment condition (no modelling with no instruction, instruction alone, modelling alone, and instruction with modelling) and sex. Mental and chronological ages were included as covariates. The results showed that (a) the strategy adoptions were more frequent in the instruction with modelling and in the instruction alone conditions than in the control condition and the modelling alone condition was not different from the control condition, (b) PNG children in the three experimental conditions adopted the advocated strategy about three times as often as the Australian children, (c) no differences occurred between girls and boys in strategy adoptions but girls were quicker in completing the tasks than boys, and (d) chronological age was a predictor of group effects. These results were discussed in terms of a possible cognitive developmental mechanism in the performance of modelled behaviours.