This paper is my second attempt to build up the "frame of reference" of media & communication studies which include areas of public communication, public relations, mass media and journalism. (My first paper was published in this Journal, No.2, 2004.) If these four areas of practical activities constitute "a single disciplinary science", it seems to me that there must be some frame of reference according to which we could determine significance and locations of these four activities in the social system. It is obvious that public communication, public relations, etc. are social interactions, and therefore T. Parsons'original scheme of pattern variables might give us some possibilities of applying his theory of action to our "media & communication studies".