Identifying, acquiring, and developing valid and reliable instruments are major problems facing researchers who study psychosocial drug use and abuse. Much time is often devoted to creating a measuring device when an adequate one already exists, resulting in duplication of effort, considerable waste of resources, and loss of uniform comparability of data. Furthermore, few guidelines exist to aid in the arduous task of designing new instruments and items. What areas or variables should be assessed? How have others attempted to assess these areas? How should the items be presented? This handbook is designed to help eliminate these problems. It is intended to serve as a basic reference tool by identifying existing instruments and suggested items for the creation of new instruments. Over 2,000 items from 40 instruments are included, categorized according to the areas they assess. The instruments from which they were selected have been found to discriminate between drug users and nonusers, or have identified different drug user types. Many of the instruments were developed specifically for drug research; others were developed first for use in other fields. It is hoped that this unique handbook will facilitate contact between instrument developers and users, and enable other investigators to compare and build upon previous research. (Author)