The initiation of a research project requires many decisions, not the least of which is the selection of a method for data collection. This decision is, in large measure, guided by the nature of the research question which generally prescribes the selection of a strategy for data collection from among an array of possible alternatives. This article addresses the use of a diary for data collection. Although diaries have traditionally been used in social science and health research, their use in nursing research is more recent. The article begins with a brief discussion of the rationale for using the diary to gather data in a study of personal and professional care giving. A brief review of the use of diaries in previous studies follows, along with a description of the use of a diary in the caregiving study and a discussion of the possible threats to high quality data as well as measures used to ensure the collection of high quality data The article concludes with a discussion of the strengths and weaknesses of the diary andmakes recommendations regarding its use in nursing research.