The present paper outlines the relevance of cheerfulness, seriousness, and bad mood for humor research. A state-trait model of exhtiaratability is presented which incorporates the three concepts äs both states and traits. Definitions of the concepts are undertaken utilizing a facet approach and the relationships among the three concepts are outlined. The construction strategy for the various forms of the German Version of the State-Trait- Cheerfulness-Inventory (STCI) is outlined and the following versions of the trait form will be elaborated: (a) the pilot form with 122 items (STCI-T<122>); (b) a component (or long) form with 106 items (STCI-T<106>); (c) the Standard form with 60 items (STCI-T<60>) and (d) the international form with 106 items (STCI-T<106i>). The development ofthe twoforms, the replication ofthepsychometric character- istics, and the evaluation of the facet model utilized samples of German and American adults comprising more that 1,300 subjects altogether. The hypothesized facet structure emerged and appeared to be highly generaliz- able across the samples. The psychometric characteristics ofthe facets and scales appeared to be satisfactory. While there were no sex differences in any of the scales, seriousness increased steadily öfter age 40. Correspondence between seif· and peer-evaluation was examinedand turned out to be sufficiently high. The construction seemed to have been successful in promding a reliable Instrument for the assessment ofthe temperamental basis ofthe sense of humor.