The goal of this paper is to provide researchers who are not experts in psychometric theory with a concise guide to instrument selection, development and evaluation. Issues of context - factors related to the setting or population in which an instrument will be used - and psychometrics - the functioning of an instrument within a given context - are reviewed and discussed. Finally, four categories or types of instruments, and the psychometric analyses that are necessary for establishing the reliability and validity of each type, are described.