PROBLEM: Two problems were addressed in this study. First, are daily injury diaries an effective means to gather information about children's unintentional injuries? Second, what are the circumstances of children's injuries as recorded through the diary method? METHOD: Two studies were conducted with a total of 172 children to describe the ecology of children's daily unintentional injuries. Families completed a daily diary for 14 days, describing the circumstances surrounding the injuries children experienced each day. RESULTS: Descriptive data is provided on the locations, causes, and types of injuries children incurred, as well as who was present when they were injured. Daily injury rate was modestly related to the number of major injuries children had incurred in their lifetimes. DISCUSSION: The diary methodology was an effective means to study the ecology of children's daily injuries. Children's injuries occur in a wide range of circumstances that can be quantified through diary techniques. IMPACT ON INDUSTRY: Data obtained from daily injury diaries may be useful in a variety of areas, including study of the etiology of childhood injury, design of interventions to prevent injury, and engineering of toys and playground equipment for children.