This study analyzed possible human factors deficiencies in the design, operation and application of powered industrial trucks, powered cranes and hoists, and powered conveyors. Wisconsin Worker's Compensation case histories, accident investigations, and employee reports of injury furnished the major data base. Site visits provided the basis for the validation, refinement, and elaboration of the current categories of accidents by observing actual equipment in use. Specific design deficiencies were not critical compared to deficiencies in proper applications of the equipment, inadequacies in the use accessory tools and equipment, and general management and system shortcomings in controlling material handling hazards through the development and exchange of relevant information as to hazards and proper equipment. Failure of the above factors to combine their efforts in defining responsibilities and objectives in the safety area was the study's most critical finding. The study recommended that NIOSH, the materials handling industry, and the employers responsible for managing the equipment hazards undertake the integration of industrial, government, and worker resources for improved safety, specifically for the development of hazard and accident data and easy access to the information by all interested parties. The behavior of humans needed to be incorporated into safety and health practices along with the primarily physical specification standards of OSHA. A federally sponsored and subsidized Materials Handling Safety and Health Research Institute should be created to investigate and develop countermeasures for the operational hazards of truck, crane, and conveyor use. Correlational studies of hazards and accidents with the work process variables of change, or unexpected events and variances, and of job design were urgently needed as were improved means for informing workers of hazards and exercising more effective control over equipment safety. Human factors system principles were desperately needed for analyzing and assessing the causes and factors of hazards and injuries. The final recommendation was the integration of safety and production management to provide a total organizational commitment to safety. The study contained specific recommendations for powered conveyor systems, cranes, hoists, and trucks. Fifteen figures and twenty- seven tables depict the various types of equipment, their proper uses, sources of accidents, and safety standards.