Objectives. The purposes of this study were to examine the cross-cultural validity of the Assessment of Motor and Process Skills (AMPS) as well as the reliability of raters from different cultures. Method. Six trained raters from diverse cultural backgrounds scored 10 Japanese subjects’ performances on familiar and culturally relevant tasks of their own choosing. Results. Results indicated high cross-cultural validity and interrater reliability for the AMPS, as indicated by goodness of fit of subjects and raters via the many-faceted Rasch measurement model. The relative rater severity was also evaluated cross-culturally by the standardized difference (z). The Japanese rater and one of the three American raters varied significantly in severity between their scoring of Japanese subjects versus European subjects. Conclusion. The results support the hypothesis that the AMPS can be used as a cross cultural instrumental activities of daily living assessment. Further study is needed to clarify the issue of possible cultural bias in rater severity.