Conducting research with vulnerable populations involves careful attention to the interests of individuals. Although it is generally understood that informed consent is a necessary prerequisite to research participation, it is less clear how to proceed when potential research participants lack the capacity to provide this informed consent. The rationale for assessing the assent or dissent of vulnerable individuals and obtaining informed consent by authorized representatives is discussed. Practical guidelines for recruitment of and data collection from people in the middle or late stage of dementia are proposed. These guidelines were used by research assistants in a minimal risk study.