Landscapes in eastern Spain are characterized by a wide range of erosion susceptibility. We hypothesized that parent material and vegetation affect infiltration, runoff, and erosion. Sixty field rainfall simulation trials (55 mm during 1 h on 0.22–0.27 m2 plots) were carried out on soils formed on marl, clay, limestone, and sandstone parent material under three vegetation cover rates: 0 to 20 (bare), 40 to 60 (intermediate), and 80 to 100% (vegetated) in eastern Spain to test this hypothesis. Surface runoff and erosion were related to parent material and vegetation cover. Vegetation enhanced infiltration and reduced surface runoff and erosion, and their variability decreased as vegetation cover increased. For bare soils, the steady-state infiltration rates ranged from 3 to 55 mm h-1, the runoff from 0 to 83%, and the erosion rates from 0 to 3720 g m-2 h-1. On the vegetated soil, the values were 53 to 55 mm h-1, 0 to 9%, and 0 to 6 g m-2 h-1, respectively, for infiltration, runoff, and erosion rates. Runoff and erosion were greatest for marl soils (0–83% and 0–3720 g m-2 h-1, respectively) and intermediate for clay and limestone (0–46% and 0–131 g m-2 h-1). Sandstone generated negligible water and soil losses (0–7 % and 0–0.29 g m-2 h-1). The interaction of vegetation and parent material showed that, on marl soils, plant cover was the main factor preventing high runoff and erosion rates.