In this study, we wished to investigate whether the use of tailored nutrition education letters addressed to each family member simultaneously at home could serve as a valuable strategy for nutrition education, Family quartets (both parents and two adolescents, all healthy individuals) were chosen to be the units of intervention, The first aim of our study was to investigate the impact of tailored versus standardized nutrition education on fat intake and on psychosocial determinants of fat intake in families, using a randomized dietary feedback study. Our second aim was to study the differential effect of the tailored nutrition education on different family members. Analyses were conducted among 18 experimental families (n = 72) and 17 control families (n = 68). The tailored intervention was more effective than the nontailored intervention in reducing total and saturated fat intake when all the family members were included (F = 4.0, P <0.05 and F = 5.9, P <0.05). However, follow-up analyses revealed that only mothers benefit from the tailored intervention(F = 6.4, P <0.05 and F = 10.2, P <0.005). For fathers and adolescents, both interventions resulted in a significant decrease in fat scores. Furthermore, tailored feedback resulted in stronger awareness of personal fat intake and awareness of fat intake of family members. Tailored advice has the potential to communicate the personal need to change. As differences in fat reduction between family members receiving general or tailored nutrition education letters were smaller than expected, future research will have to prove that family-based tailored interventions are more effective than standardized interventions and interventions focusing on a single person. It also needs to be clarified why mothers in particular benefit from tailored feedback.