Amer­i­can Jew­ish iden­ti­ty has changed sig­nif­i­cant­ly over the course of the past half cen­tu­ry. Dur­ing this time, Irv­ing Green­berg devel­oped a unique the­ol­o­gy that antic­i­pat­ed David Hollinger’s notion of posteth­nic­i­ty and rep­re­sents a com­pelling under­stand­ing of con­tem­po­rary Amer­i­can Jew­ish iden­ti­ty. Green­berg’s covenan­tal the­ol­o­gy and image of God idea com­bine into what Klein­berg refers to as Hybrid Judaism. Cen­tral to Green­berg’s the­ol­o­gy is recog­ni­tion of the trans­for­ma­tive pow­er of encounter in an open soci­ety, heav­i­ly influ­enced by his own encoun­ters across Jew­ish denom­i­na­tion­al bound­aries and through his par­tic­i­pa­tion in the Chris­t­ian-Jew­ish dia­logue move­ment. Pre­sent­ed here for the first time, Green­berg’s the­ol­o­gy of Hybrid Judaism has great rel­e­vance for our under­stand­ing of Amer­i­can Jew­ish iden­ti­ty in the twen­ty-first century.