Large-scale hydrological drought studies have demonstrated spatial and temporal patterns in observed trends, and considerable difference exists among global hy-drological models in their ability to reproduce these patterns. In this study a controlled modeling experiment has been set up to systematically explore the role of climate and physical catchment structure (soils and groundwater systems) to bet-ter understand underlying drought-generating mechanisms. Daily climate data (1958–2001) of 1495 grid cells across the world were selected that represent Köppen–Geiger ma-jor climate types. These data were fed into a conceptual hy-drological model. Nine realizations of physical catchment structure were defined for each grid cell, i.e., three soils with different soil moisture supply capacity and three groundwa-ter systems (quickly, intermediately and slowly responding). Hydrological drought characteristics (number, duration and standardized deficit volume) were identified from time se-ries of daily discharge. Summary statistics showed that the equatorial and temperate climate types (A-and C-climates) had about twice as many drought events as the arid and po-lar types (B-and E-climates), and the durations of more ex-treme droughts were about half the length. Selected soils un-der permanent grassland were found to have a minor effect on hydrological drought characteristics, whereas groundwa-ter systems had major impact. Groundwater systems strongly controlled the hydrological drought characteristics of all cli-mate types, but particularly those of the wetter A-, C-and D-climates because of higher recharge. The median num-ber of droughts for quickly responding groundwater systems was about three times higher than for slowly responding sys-tems. Groundwater systems substantially affected the dura-tion, particularly of the more extreme drought events. Bi-variate probability distributions of drought duration and stan-dardized deficit for combinations of Köppen–Geiger climate, soil and groundwater system showed that the responsiveness of the groundwater system is as important as climate for hy-drological drought development. This urges for an improve-ment of subsurface modules in global hydrological models to be more useful for water resources assessments. A foreseen higher spatial resolution in large-scale models would enable a better hydrogeological parameterization and thus inclusion of lateral flow.