This study compared the characteristics of 'good mothers' of children with ASD (Autism Spectrum Disorder) as perceived by mothers of children with ASD in two countries--the U.S. and Japan. Grounded in the theory of culturally-influenced construal of the self, we hypothesized that U.S. mothers would prioritize fostering self-reliance and advocating for their child's well-being while Japanese mothers would prioritize maintaining close and harmonious relationships with their child. We conducted semi-structured interviews with 52 U.S. and 51 Japanese mothers of children with ASD about the characteristics of a good mother of a child with ASD (GMA) and characteristics of a good mother in general (GMG) and compared the frequencies of 'good mother' categories emerging from thematic analysis. Mothers of children with ASD in both countries viewed guiding children as the most important characteristic for both GMG and GMA. As hypothesized, U.S mothers tended to emphasize a mother's active role in advocating for her children, getting her child services and intervention, and educating herself about ASD. In contrast, Japanese mothers tended to value a mother's ability to accept her child, know her child well, and provide adequate support for her child based on a child-oriented perspective. The mother's role of advocating for her child and educating herself emerged more frequently in responses regarding GMA than GMG in the U.S. sample. The study revealed cultural differences in characterization of GMA, suggesting that more indirect models of instruction may be effective for different cultural groups.