This study examined the behaviors of black Head Start children and their mothers around a series of experimental joint reading contexts in their homes. There were 2 specific objectives: (1) to examine the effects of text genre (narrative and expository) and text format (familiar and traditional) on mothers' teaching strategies while interacting with their children around reading tasks, and (2) to examine the effectiveness of mothers' teaching strategies in eliciting children's participation in the joint reading tasks. 13 mother-child dyads were videotaped in their homes while interacting around a series of texts in each genre and format. Results indicated that genre, not format, affected mothers' teaching strategies. Further, mothers adjusted their level of teaching to children's level of task competence. Results are discussed in terms of Vygotsky's notion of the zone of proximal development.