The U.S. Bureau of Mines conducted a series of tests using dewatered total tailings from three U.S. metal mines to determine the engineering and pumping characteristics for backfilling. The tests were unique because pulp densities of the samples were all above 75 pct solids, creating nonsettling, homogeneous slurries or pastes. The engineering properties tested included dry density; slump; percent settling after 28 days of curing; tensile strengths after 28, 120, and 180 days of curing; and unconfined compressive strengths after 7, 28, 120, and 180 days of curing. Properties of backfill mixtures made from tailings from the three mines were analyzed using linear and nonlinear statistical methods. Graphical results provided a predictive tool with which to select binding materials and proportions to create a backfill with the desired engineering properties. Six large-scale pumping tests were conducted using cemented and uncemented paste backfills made from two of the tailings included in the property tests. The pastes were mixed to similar consistencies to compare the friction losses at various flow rates through a loop consisting of pipes of three different diameters.