Content experts frequently are used in the judgment-quantification stage of content validation of instruments. However, errors in instrumentation may arise when important steps in selecting and using these experts are not carefully planned. The systematic process of choosing, orienting, and using content experts in the judgment-quantification stage of instrument development is addressed, with particular attention to the often neglected, important step of familiarizing these experts with the conceptual underpinnings and measurement model of the instrument. An example using experts to validate content for a measure of caregiver burden is used to illustrate this stage of instrument review. © 1997 John Wiley & Sons, Inc.