The scaffolding strategies naturally employed by parents while reading with children have been shown to vary between families, though few studies have addressed factors influencing strategy choice. The present study investigated the impact of children's degree of shyness and decoding ability on parent behaviours surrounding difficult words encountered during shared book reading, as well as their influence on children's own behaviours. Grade one children and their parents were observed reading storybooks at home. Results suggest that parents chose more directive and protective strategies when coaching shyer and poorly skilled readers. Children's approaches to difficult words did not vary with their shyness, possibly because the familiar nature of the reading experience attenuated existing differences. However, children's approaches were predicted by their reading ability and sex. Boys more frequently guessed at unknown words, while girls and poorer readers were more likely to pause or request assistance.