Two important sources of error that may limit the accuracy of individual family members' projections of joint family preferences are: (i) misperceptions of other members' preferences, and (ii) misperceptions of other members' influence in joint family evaluations. We propose a two-stage conjoint approach to study these potential errors. Stage one compares family members' projections of each other's preferences to members' self-reported preferences. Stage two compares family members' projections of each other's influence to observed influence in joint family preferences. An empirical illustration shows that family members are relatively poor predictors of preference, but fairly accurate predictors of influence, in the area of family holiday preferences.