On Sunday, the twelfth of Adar, March 2, 1681, the parnasim, the lay leaders of Altona, recorded an enactment in their communal logbook, the pinkas kehillah, regulating women's use of the local mikva'ot. Designating two privately-owned ritual baths as the only approved immersion locations for most of the women in the community, they decreed that defiance of this decree was to be punished with some of the most severe weapons in the arsenal of the communal leaders. Four years later, the parnasim reversed their policy and, with the permission of the community's rabbinic leadership, required the women to use only the newly built kahalishe, or community, mikveh, banning the use of the two previously approved mikva'ot. This article examines the construction and reconstruction of these policies regulating women's use of mikva'ot, offering insight into how designated communal institutions were developed in the early modern period as well as how these institutions were used both to finance the community and to forge communal identity. Moreover, consideration of the mikveh as a locus for building communal institutions and, in particular, communal identity, offers insight into how the growing bureaucratization of Jewish communal life in the early modern period affected women's lives.