"ARL Statistics 2006-2007" is the latest in a series of annual publications that describe collections, staffing, expenditures, and service activities for the 123 members of the Association of Research Libraries (ARL). Of these, 113 are university libraries and 10 are public, governmental, and nonprofit research libraries. Data reported by libraries are presented in a series of tables. In addition, trends in service activities, serial unit costs, and ownership and access are highlighted and their implications for libraries discussed. The following are appended: (1) ARL Member Libraries as of January 2008; and (2) Bibliography. [For "ARL Statistics, 2005-06: A Compilation of Statistics from the One Hundred and Twenty-Three Members of the Association of Research Libraries," see ED501323.]