Multiple inventories claiming to assess the same explicit motive show only mediocre convergent validity. In three studies the structure, nomological net, and content coverage of multiple existing motive scales was investigated with exploratory factor analyses. The analyses revealed four approach factors and a general avoidance factor with a facet structure. New scales were developed using IRT, reflecting these underlying dimensions. In comparison to existing questionnaires, the UMS have the highest measurement precision and provide short and ultra-short scales. In a fourth (...) study, the UMS demonstrated incremental validity over existing motive scales with respect to several outcome criteria. (shrink)