This essay addresses the problem of the relation between membership and moral responsibility in the interpretation of the doctrines of original sin and atonement by Jonathan Edwards. Focusing on his image of a tree and its branches to typify the solidarity of men as sinners (“in Adam”) and as saints (“in Christ”), I will argue that Edwards defines the “nature” of man in organic and historical terms which modify significantly both the biological images of infection and regeneration in the Augustinian-Calvinist tradition and the juridical terms of federal headship in Puritan covenant theology. Edwards defines “membership” in the race of Adam, as well as in the body of Christ, as a form of participation in a history which is decisively shaped by the disposition of its organizing figure. Yet, in formulating the doctrines of original sin and atonement, Edwards is careful to maintain the balance between disposition as a generic characteristic and action as an individual responsibility. Edwards' theory of solidarity, informed by a sense of history as the medium of ethical relationship, is an instructive attempt to clarify the relation between curse and disobedience, as well as that between grace and faithfulness.