If natural kinds were defined on the basis of fixed and immutable essences, then – with the end of essentialism in life sciences – their end, at least for those kinds confined to the living realm, would ensue as well (1-2). If appropriately revised and adapted, however, natural kinds may still play an important theoretical role, not only for the sake of philosophical speculation, but also in accomodating scientific practices and in providing an adequate rendering of human reasoning. The proposal outlined in this paper moves from the historical and disjunctive solutions of Millikan and Boyd, but it departs from them in that it offers a conventionalist interpretation of natural kinds. The bulk of the theory is presented through the case study of the distinction between sexes and genders (3). A few remarks on how to further the proposal are offered in the final section (4).