The current study describes from an attachment-theoretical viewpoint how intergenerational support in adult child-parent relationships is associated with wellbeing in both generations. The attachment perspective and its focus on affective relationship characteristics is considered as an important theoretical framework for the investigation of special relationships across the life span. Data from the Netherlands Kinship Panel Study (N = 1,456 dyads) were analysed to investigate if relationship quality moderated the association between providing intergenerational support to parents and wellbeing in adult children, on the one hand, and receiving intergenerational support from children and wellbeing of older parents on the other hand. The perspectives of both relationship partners were taken into account to allow for dependence within dyads. Intergenerational support, in terms of instrumental help provision, was negatively associated with the child's and parent's wellbeing. Being the stronger and wiser partner in adult-child parent relationships, as reflected by giving advice and being the initiator within the relationship, was beneficial for the wellbeing of both generations. Additionally, relationship quality was the strongest predictor of wellbeing in both generations. Parental wellbeing was benefited by filial support in high quality relationships. If an intergenerational relationships was of high quality, the challenges of intergenerational support provision and receipt were easier to deal with for both generations, parents and children. © 2009 Cambridge University Press.