AbstractThe new edition ofJournal Citation Reports (JCR), based on a complete year of 1974 data, extends the scope of the preliminary edition which was based on one quarter year of 1969 data. It is published as a bound companion volume to the 1975Science Citation Index (SCI)and lists 1974 citing journals and the earlier journalscitedby them. Some 2,400 1974 citing journals are covered and these journals contained about 4.2 million references to earlier journal items. For each journalJCRshows the total number of citations received by 1972 and 1973 volumes, and by all years. It also shows the number of articles published in the cited journal in 1972 and 1973‐that is the articles available for citing in those years. From this data theimpact factoris calculated—the average number of 1972/1973 citations received by each 1972/1973 article. This discounts the effect of size (larger journals receive more citations).JCRalso shows the number of articles published in each cited journal during 1974, and the number of 1974 citations to them from all other journals. Theimmediacy indexis the average number of times each 1974 article was cited in 1974. FinallyJCRshows, for each journal, the journals which cite it most heavily, and the journals which it cites most heav