Certain types of mobile surface mining equipment are required to be equipped with rollover protective structures (rops) capable of protecting the operator in case of a rollover accident. The Bureau of Mines has developed rops performance criteria for wheeled front- end loaders. This report reviews the development of rollover test procedures and subsequent testing of rops for 52,000-, and 286,000-, and 390,000-lb gross vehicle weight (gvw) loaders. The program consisted of both dynamic (roll) and static tests to assist in the development of the rops performance criteria. Each test included extensive instrumentation and photographic documentation to fully evaluate the performance of the rops. Data summarizing side, longitudinal, and vertical force and deflections are included. The data indicate that for loaders in excess of 240,000 lb, gvw, a side force-to-mass ratio of 1.0 and an energy-to-mass ratio of 6.0 Appear to be adequate criteria to protect an operator in the event of a 540 deg rollover. For smaller machines, Society of Automotive Engineers (SAE) J1040 performance criteria provide adequate protection. Longitudinal loading, though not adressed in previous rops performance criteria, was shown to be a potentially significant factor in rops failure. Longitudinal loading and energy criteria equal to 80 pct of side loading criteria are recommended.