Two studies were conducted to examine the characteristics and structure of 12 achievement-related affects. In Study I, 224 undergraduates rated the 24 concepts (12 affects×2 items) on the three scales (with six 7-point semantic differential-type items per scale) of pleasure-displeasure, arousal-nonarousal and dominance-submis-siveness. The results showed that these three dimensions were also valid to define the structure of achievement-related affects, and dominance-submissiveness dimension had the most important roles on the descriptions of the characteristics of affects. In Study II, the ratings concerning the list of affective words obtained in Nasu and Horino (1991) were cluster analyzed. In analysis, two large clusters were revealed. The affects included in the first cluster were “mastery oriented” affects. On the other hand, the second cluster represented “helpless oriented” affects (Dweck, 1975), or affects related to “ego-involved” tendencies (Nicholls, 1984).