The representation of women in Blake's poetry and its role in his revisionist Christian system have drawn considerable critical attention in Romantic studies. In the existing studies on the Blakean woman, the frequent images of “harlot” and “whore” are interpreted as his criticism of sexual repression and plantation slavery as well as a device of biblical allusion. But even with his most allusive and metaphorical depictions of the harlot, Blake shows his engagement with the changing social perceptions of prostitution and the gender ideologies and institutions established around such perceptions. This paper proposes that Blake was aware of the significant transformation of how the prostitute was viewed in the eighteenth century: from a siren-like embodiment of boundless lust to an unfortunate victim of external circumstances. Moreover, he was aware of the social view that reformed prostitutes could redirect “wasted” sexual passion along the path of productivity. This transformation and its relation to social and political contexts can be discerned in Blake's juxtaposition of the harlot and her supposed antithesis, the mother, which demonstrates a poignant critique of the ideal motherhood of his time.