This study investigates relationship quality of women with their mothers and mothers-in-law and how relationship quality is affected by providing instrumental support. This longitudinal study extends the research by exploring the effects of support giving over time on the daughter/mother relationship and on the daughter-in-law/mother-in-law relationship;Based upon social exchange theory and role theory, the central hypothesis for this study is instrumental support given and perceived demands will erode relationship quality over time. As support giving increases, social exchange theory suggests that the support giver feels an imbalance in rewards verses costs and this perception negatively affects the relationship. Role theory also makes the argument that as demands of a particular role increase, role overload from that one role can occur. The resulting stress can negatively affect relationship quality over time;Subjects were 252 white, married women, drawn from three waves of a larger ongoing research project, The Iowa Youth and Families Project conducted at Iowa State University. The women were members of families with children, living in rural Iowa;Using t-tests, means of mother related variables were compared with means of mother-in-law related variables. Change in relationship quality over time with both mothers and mothers-in-law were also assessed. Pearson product moment correlations were used to determine the direction and strength of the relationships between variables. Ordinary least squares regression was used to estimate coefficients for path analyses;Results indicated that although subjects provided mothers with more instrumental support than they did mothers-in-law, mothers were not perceived as any more demanding than mothers-in-Law; While relationship quality with mothers was higher at both times than relationship quality with mothers-in-law, relationship quality with mothers and mothers-in-law were stable over time;Giving instrumental support did not affect relationship quality with mothers nor with mothers-in-law over time. However, demands of both mothers and mothers-in-law were associated with declining relationship quality over time. Giving instrumental support to mother was unexpectedly associated with lower relationship quality with mother-in-Law; This implies the occurrence of scapegoating of mothers-in-Law; The data strongly suggest that it is not the amount of support given, but rather the perception of demands made by support recipients that adversely affects relationship quality over time.