Introduction It is no exaggeration to say that prior to Vatican II most American Catholics were oblivious of the very existence of Karl Rahner. Understanding him and his prodigious theological out­ put was the almost exclusive challenge of a handful of professional theologians in this country whose task it was to decipher the complexities of his style and to grapple with the profound implications of his thought. But toward the end of the first session, press coverage of the council began to awaken a more popular interest on this side of the Atlantic. The theological renewal among laymen and movements like Sister Formation also helped sharpen the curiosity of many non-seminarians in Rahner's theological speculations.