Purpose: The purpose of this study was (a) to obtain information about the perceptions held by seniors and health care providers concerning what constitutes a fall and potential reasons for falling, and (b) to compare these perceptions to the research literature. Design and Methods: As part of a larger telephone survey, interviewers asked 477 community-dwelling seniors to define a fall and to provide reasons for falling. In addition, we interviewed 31 health care providers from the community on the same topics. In order to capture patterns in conceptualized thinking, we used content analysis to develop codes and categories for a fall definition and reasons for falling. We reviewed selected articles in order to obtain a comprehensive overview of fall definitions currently used in the research and prevention literature. Results: A fall had different meanings for different groups. Seniors and health care providers focused mainly on antecedents and consequences of falling, whereas researchers described the fall event itself. There were substantial differences between the reasons for falling as reported by seniors and the risk factors as identified in the research literature. Implications: If not provided with an appropriate definition, seniors can interpret the meaning of a fall in many different ways. This has the potential to reduce the validity in studies comparing fallers to nonfallers. Research reports and prevention programs should always provide an operational definition of a fall. In communication between health care providers and seniors, an appropriate definition increases the possibility for early detection of seniors in greater need of care and services. (Contains 4 tables, 2 figures and 3 footnotes.)