D URING the last two or three years interest has increased considerably in the problems connected with indexing and abstracting services. The A.L.A. committee, created in January, 1938, "to formulate a plan for the study and solution of the most pressing problems," has been doing valuable fundamental work; and the Association of Research Libraries has had a committee working on certain aspects of the financial difficulties confronting these services. But there has not been nearly enough action and discussion. Perhaps it is not too much to say that adequate indexing and abstracting service will be the outstanding problem of the bibliographic side of library work during the next decade. In these times of recurring economic and political crises periodical literature in all fields is steadily increasing, both in bulk and in importance. Around indexing and abstracting service-or the lack of it in some fields-is a complex array of considerations, such as coverage, editorial policy, finance, technical procedure, relation to other bibliographic services, etc. A variety of institutions, groups, and points of view are concerned. We are attempting here to define only some of the most important specific problems involved. Two facts must underlie all discussions of indexing services. First, the existing services do not cover nearly enough periodicals, both with respect to total number of titles and specific titles in important fields., Second, it is neither economically nor technically feasible-and probably not desirable-to index all periodicals. Some selection of those to be indexed is inevitable.