Evaluation and prevention of falls begin with a thorough understanding of their occurrence. Post-fall assessment (PFA) tools should be available to sufficiently guide nursing staff in identification of all possible causes. Absence of empirically tested PFA tools led to the development of the Post-Fall Index (PFI). Developed and validated in three phases, a 76-item PFI was first tested for content validity by national experts. Next, it was tested for feasibility with registered nurses practicing in nursing homes. Last, it was piloted with a sample of 30 falls by older residents of a skilled nursing unit in a continuing care retirement community. Review of data from these 30 falls provided the item analysis. Reflective of evidenced-based guidelines, a 30-item PFI emerged, containing essential items causing falls. Although lengthier than incident reports, its comprehensiveness was deemed of higher value. Large absolute agreement of items (70%-100%) indicates good interrater reliability. The PFI is valid, reliable, and feasible and has clinical utility for the secondary prevention of falls.