In recent years, self-theories such as growth mindset and resilience have gained interest as they have a sizable influence on achievement and school-related motivation. The aim of this study is to investigate the relationship between immigrant students' growth mindset, resilience, and science achievement in PISA 2018 by considering the mediating effect of attitudes toward school. Using secondary data for Australia, the UK, and the USA obtained from PISA 2018, we conducted a series of Structural Equation Modeling analyses to unravel the relationship between self-theories and science achievement. The growth mindset had the strongest effect on science achievement for both immigrants and non-immigrants in all three countries; resilience was positively related to science achievement for immigrants in the US, and attitudes toward school were positively related to science achievement for immigrants in Australia. The mediating role of attitudes toward school between growth mindset, resilience and science achievement could not have been confirmed. We speculate that self-theories might be affecting immigrant groups differently in different countries. Implications regarding these findings are discussed.