Self/other agreement between self-concept ratings by the individual and self-concepts inferred by significant others is of theoretical and practical importance, but the review by J. S. Shrauger and T. J. Schoeneman (1979) found no evidence for such agreement. In the present investigation, the Self Description Questionnaire III (SDQIII) was completed by 151 Australian and 941 Canadian university students and by significant others selected by students as the person in the world who knew them best. Self/other agreement on each of the 13 SDQIII scales was very high for Australians and Canadians. Guidelines for evaluating multitrait-multimethod (MTMM) data and a confirmatory factor analysis (CFA) approach strongly support convergent and discriminant validity. An important new extension of the MTMM CFA approach to multistudy data showed that all parameter estimates were reasonably invariant (i.e., equal) for Australians and Canadians. This self/other agreement is much higher than found elsewhere and its replication across two continents dramatically refutes the Shrauger and Schoeneman conclusion. Critical features leading to this high self/other agreement appear to be the use of older subjects, multiple dimensions of self-concept based on instruments with strong psychometric properties, and significant others who know the subject very well. A 47-item list of references is included. Seven data tables and a list of means, standard deviations, and correlations among 26 study variables are provided. (TJH)