Investigated Japanese affective structure and its relation to English-language mood in an idiographic/nomothetic analysis. 57 Japanese mood terms were derived from an initial pool through factor analysis of content sortings. 18 Japanese undergraduates provided daily self-ratings on these terms for 3 mo. Each Ss' data were subjected to an individual factor analysis. Two large factors—Positive and Negative Affect, the major dimensions of mood found in previous research among English-speaking US Ss—emerged in most of the solutions. Japanese/English bilinguals made content sortings of the Japanese terms and 60 English mood words. The resulting 15 bilingual content categories were used in a comparison of Japanese and US mood structures, and a remarkable convergence was revealed. Factor score distributions were also similar in the 2 languages. The major difference between the structures involved the content factor Sleepy, which did not have a significant negative loading on the Japanese Positive Affect factor. This appears to be consistent with known cultural differences in values and behavior.(43 ref)(PsycINFO Database Record (c) 2017 APA, all rights reserved)