Shared picture-book reading is well-recognized as beneficial for children's early language development, especially where “dialogic book-sharing” techniques are used. Possible benefits of dialogic book-sharing to other aspects of child development have been little investigated, and it has not been widely studied in European populations. We conducted a randomized trial of dialogic book-sharing in Children's Centers in the UK, with parents of 2- to- 4-year-old children, hypothesizing that it would benefit parenting and a range of child developmental outcomes. Intervention group parents (n = 110) received 7, weekly, group training sessions, and control parents (n = 108) the usual center input. Parenting and a range of child outcomes (language, attention, executive function, social development, and emotional-behavior difficulties) were assessed on 3 occasions: before, after, and 4–6 month following intervention. For all study outcomes we compared controls with each of the Intention-to-Treat population and the per-protocol population (participants attending the requisite number of sessions); and, for primary child outcomes only, the population of parents who engaged well with the intervention. There were substantial benefits of dialogic book-sharing training to parental behavior during book-sharing, especially for sensitivity and cognitive scaffolding. For all 3 sets of comparisons there were small-medium effects of on child expressive language, and, for the per protocol and engaged populations, similar sized effects on child receptive language and attention. There was no evidence of benefit of dialogic book-sharing for the other areas of child development; we suggest that specific intervention components need to be added to standard dialogic book-sharing to effect change in these areas.