This paper is concerned with the relations between the individual characteristics (Temperament, Locus of Control, Self-concept) of Cyear-olds, child-mother and child-sibling interactions. The temperamental characteristics Active and Moody, and the Selfconcept categories WorryinglCross and Likes to be Alone, had generally similar relations to child-mother and child-sibling interactions, but the other characteristics did not. The relations between child-mother and child-sibling interactions did not support either the hypothesis that a 'good' child-mother relationship leads to 'good' interactions with a sibling, or that firstborns compensate for a 'poor' child-mother relationship with a 'good' sibling one. The relations were more complex than either of these hypotheses would suggest, but made intuitive sense.