This study examined mother-child shared book reading behaviors before and after participation in a random-assignment responsive parenting intervention called Play and Learning Strategies (PALS) that occurred during infancy (PALS I), the toddler-preschool (PALS II) period, or both as compared with a developmental assessment (DAS) intervention (DAS I and/or II). The efficacy of PALS was previously demonstrated for improving mother and child behaviors within play contexts, everyday activities, and standardized measures of child language. We hypothesized that PALS effects would generalize to influence maternal and child behaviors during a shared reading task even though this situation was not a specific focus of the intervention and that this would be similar for children who varied in biological risk. Participation in at least PALS II was expected to have a positive effect due to children's increased capacity to engage in book reading at this age. Four groups of randomized mothers and their children (PALS I-II, PALS I-DAS II, DAS I-PALS II, DAS I-II) were observed in shared reading interactions during the toddler-preschool period and coded for (a) mother's affective and cognitive-linguistic supports and (b) child's responses to maternal requests and initiations. Support was found for significant changes in observed maternal and child behaviors, and evidence of mediation was found for the intervention to affect children's behaviors through change in maternal responsiveness behaviors. These results add to other studies supporting the importance of targeting a broad range of responsive behaviors across theoretical frameworks in interventions to facilitate children's development. (Contains 8 tables and 1 figure.)