The Fortran 90 computer language is not just the long-awaited updating of Fortran to modem computing practices. It is also at the cutting edge of a much wider revolution in computing, that of multiprocessor computers and widespread parallel programming, a revolution rapidly moving to the desktop. Numerical Recipes in Fortran 90, as Volume 2 of the Fortran Numerical Recipes sertes, takes up where Volume 1 (now available as Numerical Recipes in Fortran 77) leaves off. Volume 2 (this volume) begins with three completely new chapters that provide a detailed introduction to the Fortran 90 language and then present the basic concepts of parallel programming, all with the saure clarity and good cheer for which Numerical Recipes is famous. The authors explain why Fortran 90, and the general approach of "thinking parallel" that they advocate, is of immediate benefit to all scientific programmers, even on today's single-processor PCs and workstations, and even before multiprocessor machines arrive on the desktop. Routines coded with parallel language features are usually shorter, clearer, and doser to the underlying scientific ideas than their traditionally coded, do-loup laden counterparts. All 350+ routines from the second edition of Numerical Recipes are in this volume, almost all of them completely reworked algorithmically so as to be "parallel-ready" and to utilize Fortran 90's advanced language features. The introductory discussions and mathematical derivations of Volume 1 are not repeated in this volume (it is assumed that the reader will use this volume in conjunction with Volume 1), so the text discussion that accompanies the individual routines focuses instead on Fortran 90 language tips, and on conceptual "parallel hints." Numerous such discussions are sprinkled thoughout this volume. Also included is a foreword by Michael Metcalf, one of Fortran 90's original designers.