The current study examined psychometric properties of the Japanese version of Abbreviated Multidimensional Acculturation Scale (AMAS-ZABB-JP) and the 20-item Multigroup Ethnic Identity Measure (MEIM-JP) with 273 Japanese sojourners and immigrants to the United States. The theoretical six-factor structure for the AMAS-JP and two-factor structure for the MEIM-JP was consistent with the literature. The subscales of the AMAS and MEIM showed expected patterns of correlation with each other and with additional variables (i.e., number of years in the United States), providing evidence for construct validity. Cronbach’s alpha reflected high levels of reliability for both scales. Despite strong psychometric findings, there were translational and cultural-based findings that suggest the need for further research.