This paper is related to a similar statement presented at a Federal Trade Commission Symposium on Media Concentration. It was submitted by the Authors Guild to Senator Edward Kennedy's Subcommittee on Antitrust and Monopoly on May 10, 1978. It is one of several memoranda by the Guild opposing the acquisitions and mergers they feel have given conglomerates and large publishing companies increasing control over major lines of book publishing commerce. This statement discusses the following subjects: the antitrust law's prohibition on undue concentration in any relevant line of commerce within book publishing; conglomeration and concentration in book club/mail order publishing, in mass market paperback publishing, and in trade book publishing; the impact of this concentration on independent trade book publishers and authors and on the security of the First Amendment marketplace of ideas; and the effect of this concentration on the publishing industry's ability to fulfill its social and cultural responsibilities. (MKM)