Previous studies on reciprocity of support in parent–child relationships during adulthood have focused on the needs of the recipient and other characteristics of the relationship, whereas the role of personality characteristics is not yet well understood. In the present research, we explored how prosocial dispositions and prosocial behaviour of both parents and adult children relate to perceptions of their relationship as reciprocal with respect to support. Family social relations models were applied to disentangle general relationship behaviour and perceptions from effects unique to the parent–child relationship. Study 1 demonstrated that results based on ‘conventional’ analytic approaches differed markedly from conclusions drawn from social relations models: the former approach indicated parents to report providing more support than their children, the latter approach revealed no differences between parent and adult child regarding their unique relationship. Study 2 extended the findings of Study 1 by focusing on behavioural mediators of the association between prosocial dispositions and perceptions of reciprocal support. Together, the findings provide insight into interdependencies among parents and children and the predictive power of individual as well as behavioural factors for understanding reciprocity of support. Furthermore, they highlight how the interpretation of parent–child relationships depends on the chosen methodological focus. Copyright © 2010 John Wiley & Sons, Ltd.