The primary purpose of this study is three-fold: (1) To explore the extent of support for and opposition to the women's movement within the Roman Catholic Church; (2) To identify which subgroups of the population have the greatest grievance with the current situation of women in the church; (3) To apply Ennis and Schreuer's (1987) theoretical concepts of grievance, efficacy and costs to Catholics' participation in the women's movement in their church. The sample consisted of 254 female and 105 male Catholics from a midwestern state. The results of this study show that the majority of Catholics questioned support the expansion of women's roles in the Church to include the deaconhood (74.8%) and the priesthood (58.9%). Overall, women reported a significantly greater grievance with the current situation of women in the church than men. Greater levels of grievance were also found among the younger and more highly educated. Among men in the sample, greater levels of parish involvement were positively related to levels of grievance. The two most important determinants of actual participation in the Catholic women's movement for both men and women are education level and parish involvement. The study found men and women are equally likely participants in this movement. The concepts of efficacy and cost, significant determinants of participation in the Ennis and Schreuer study (1987) were not found to be important predictors of participation in the Catholic women's movement. Although this study does have limitations because of the representativeness of the sample, the findings challenge prevailing theory regarding the relationship between efficacy, cost and social movement participation and by implication, the nature of institutional change.