Handbook for Scientists and Engineers is a new reference book that deals with estimating and testing a proportion or the probability of an event. The purpose of the book is twofold: it aims at providing practitioners with refined and easy-to-use techniques as well as initiating a new field of research in theoretical statistics. The book contains completely new interval and point estimators as well as test procedures that are superior to the traditional ones. This is especially true in the case of small and medium-sized samples, which are characteristic for many fields of application. The procedures are derived for fixed and bounded parameter ranges, thus allowing the selection of a method tailored to a given situation. Thus, according to the size of the proportion or probability of interest different estimators should be used, similar to the case of measuring length, where the measurement method depends heavily on the size of the length to be measured. The approach yields more precise estimators and more powerful tests. It may also be applied to other estimation or test problems.