Abstract Objective: The purpose of this study was to translate the Environmental Assessment Tool–Higher Care (EAT-HC) into Japanese and validate its use in small-scale group living facilities in Japan. Background: Environment of a facility is shown to improve its residents’ quality of life (QOL). Japan’s “welfare-based nursing homes for the elderly” are gradually shifting to a small-scale group living concept called group care units (GCUs). However, there is no appropriate environmental tool available for evaluating GCUs. The application of valid environmental assessment tools brings about a better understanding of the nature of good environments and the relationship between environments and outcomes for residents living with dementia. Methods: The study had a mixed method design conducted in several steps, covering translation and adaptation. The translation phase involved (1) forward translation and (2) backward translation. The adaptation phase involved (3) content validity and homogeneity reliability and (4) concurrent validity and interrater reliability. Results: 71 Items (92%) met the acceptable level of content validity (item-content validity index [CVI] >.79) and had good scale-CVI of.88. Concurrent validity was confirmed between.65 and.78 (p