The second edition of "Formulas, Facts and Constants" has been enlarged without undue increase in volume. The constants have been revised to 1986 values. Prom~ted by comments of many readers a section on error analysis has been added. host impor tantly, the new edition now has a subject index in addition to the detailed Table of Contents. The basic format has not been changed and the aim of the book remains to be a handy source of formulas, conversion factors and constants for everyday use. Fundamental tools of mathematics needed in all areas of the physical sciences are given in Section 1. Conversion factors and fundamental constants are 1 isted in Section 2. Section 3 gives information on terms and facts of spectroscopy and atomic structure. Section 4 reviews basic elements of wave mechanics. Section 5 is a resource for work in the laboratory and is intended to be of assistance in the use of frequently encountered equipment such as electronic devices, detectors, vacuum systems, etc. Material constants and other data frequently needed for esti mates and problem solving are provided. This new edition is dedicated to the memory of my father, Kurt Fischbeck, who was instrumental that this book was written in the first place. I have benefitted from his experience as an editor and author. He died shortly before the first edition appeared in print. I wish to thank my colleagues Jack Cohn and Stewart Ryan for their useful comments.