The impact wear resistance of two aluminum alloys was investigated using flat-ended aluminum specimens impacted upon a stainless steel counterface. The counterface itself was held stationary in some tests (pure normal impact) and moved transverse to the normal impact direction in other tests (compound impact). The alloys investigated were aluminum-copper: 2011-T3 which was formulated for free-machining applications and 2124 which possessed very high fracture toughness. Thus, one alloy favors crack nucleation and growth, while the other suppresses these. A variety of tests were conducted with both alloys in compound impact loading. The peak impulsive stress was found to influence wear rates significantly; the relative sliding velocity is also an important parameter. Surface and subsurface microscopy were used to define operative wear mechanisms. With the 2011-T3 alloy, the characteristic subsurface features support the delamination theory of wear. With the 2124 alloys, subsurface features differ significantly. These features are discussed in the light of microstructural variations in the alloys.