We describe the development and pilot testing of the St. Louis Assessment of Fall Risks, a worksite audit to assess fall prevention safety practices on residential construction sites. Surveillance data and feedback from carpenters and safety instructors regarding work tasks associated with falls from heights were used to develop the audit instrument. The audit focuses on the framing process, including general safety climate/housekeeping, floor joist/sub-floor installation, walking surfaces/edges, wall openings, truss setting, roof sheathing, ladders, scaffolds, and personal fall arrest equipment. The audit was tested at sixteen residential construction sites, documenting excellent inter-rater reliability (kappa = 0.93). Results suggest that the audit has good face and content validity and is a reliable instrument for measuring fall safety risks at residential construction sites. It is practical, easy, and safe to administer, making it a potentially useful instrument for field research as well as regular safety monitoring by foremen and crew.