This study examined how in-the-moment behaviour of children and family literacy programme use are associated with the affective quality of mother-child interactions and the content of maternal utterances that occurred during book reading. Ninety-Two Latina mother-child dyads were included. Mothers frequently exhibited warm/positive behaviour and discussed the immediate content of the book. Children were highly engaged and many of them alternated between English and Spanish when discussing the content of the book. Language mixing of children was positively associated with the number of maternal utterances on the immediate content of the book, while negatively associated with that on reading the text. Child's engagement in book reading was associated with the affective quality of mother-child interactions, but not with the content of maternal utterances. Family literacy programme use, especially parent-child interactive literacy activities service was positively associated with the number of maternal utterances on the content of the book.