We would like to thank many colleagues for their suggestions, bug reports, and (occasionally) source code. The initial development of XSTAR was promoted by Prof. Dick McCray at the University of Colorado. Contributions to the code and atomic database have come from John Raymond, Barry Smith, Ian Stevens and Yuan-Kuen Ko. Much of the impetus for work on versions 1 and 2 came from Julian Krolik. The work for version 2 could not have been carried out without programming support and advice from Tom Bridgman, James Peachey, Bryan Irby, and Bill Pence. A great deal of crucial work on the atomic data was done by Manuel Bautista, and also by Patrick Palmeri, Claudio Mendoza, Javier Garcia, Mike Witthoeft and Ming-Feng Gu. The production of this manual and the circulation of the code has been funded by NASA through the Astrophysical Data Program, Grant NAG 5-1732.