This multimethod study examined the association between family instability and children’s internal representations of security in the family system within the context of maternal communications about disruptive family events. Participants included 224 kindergarten children (100 boys and 124 girls) and their parents. Parents reported on the frequency of unstable family events, mothers reported their patterns of communication to children following disruptive events, and children completed a story-stem battery to assess their internal representations of family security. Consistent with predictions, heightened family instability was associated with less security in child representations. The implication of these results for notions of children’s security in the family system, including exploratory findings on the protective role of maternal communications for children’s representations, are discussed.