A biomechanical analysis of physical stresses associated with scaffolding tasks was performed. Observational surveys were conducted at ten construction sites in West Virginia and western Pennsylvania where scaffolding was being handled. Twenty nine workers at the sites were observed and videotaped as they carried, erected, and dismantled scaffolding. The scaffolding consisted of welded tubular frames of the open type. Different scaffold handling techniques used by the workers and how frequently they were used were determined through analysis of the videotapes. Postures associated with each of the techniques were reconstructed in a computer simulation to estimate the biomechanical stresses they imposed on different body parts. Specific task components identified in scaffolding handling included preparing the foundation, carrying scaffold components, erecting and removing end frames and cross braces, installing and removing access ladders and planks, installing and removing guard rails, and securing and removing scaffold tiebacks. Lifting scaffold end frames, carrying the end frames, handling planks, removing cross braces, and removing guardrails were task activities identified as increasing biomechanical stresses on the workers. Computer simulation of six scaffold lifting and five scaffold carrying techniques commonly used at the ten sites indicated that they would exert considerable stress on the shoulders, elbows, and hips, especially when they involved scaffold end frames that were stuck together. The authors conclude that lifting and carrying scaffold end frames are work activities that generate high levels of biomechanical stress on workers and, consequently, increase the risk of overexertion injuries. Recommendations for reducing the risk of over exertion injuries include designing lift/assistive devices to lift scaffold end frames, redesigning end frames utilizing light weight materials, and providing hand grips on the frames.