Reference librarians often encounter "instrument seekers," library users who need to find a complete psychosocial test, scale, or questionnaire to use or adapt for research or clinical use. This article focuses on the resources that can help to answer these types of questions. Reference books, monographs, journal articles, and online databases are among the kinds of resources that are described in this article. Nomenclature concerns and intellectual property issues related to utilizing tests and measures are also addressed.