In this study we compared the conversations of mothers and fathers with their children at 1;3 and 159, with special attention to breakdown-repair sequences. We found that, overall, children and secondary caregiver fathers experienced more communicative breakdowns than did children and primary caregiver mothers. More specifically, fathers requested clarification of their children more often than did mothers, and they most often used a non-specific query (e.g. What?). Mothers used more specific queries (e.g. Put it where?) and were involved in more ‘looped’ sequences involving multiple requests for clarification. Fathers also failed to acknowledge child utterances more often than did mothers. After a father non-acknowledgement, children tended not to persist and when they did they often received further non-acknowledgements; the dyad did not often return to the child's original topic. After a maternal non-acknowledgement, on the other hand, children persisted and the dyad more often returned to its previous topic. The results are interpreted as support for the Bridge Hypothesis which claims that fathers present children with communicative challenges that help prepare them for communication with less familiar adults.