This study investigates how self-efficacy and motivation predict students' science literacy and career expectations above and beyond their socioeconomic status. A structural equation model built on self-determination theory and self-efficacy was examined using PISA 2015 data from Finland and Japan. The study sample is 5882 and 6647 15-year-old students from Finland and Japan, respectively. The findings show that the model fits the data well in both countries. Intrinsic motivation is the strongest predictor of both science literacy and career expectations, while instrumental motivation predicts only career expectations in Finland and Japan. The findings for self-efficacy, on the other hand, differ across countries. It explains a considerable variance in both outcomes in Finland, whereas it predicts only career expectations with a small effect size in Japan. The findings are discussed from a cultural standpoint, with comparisons to Finland and Japan.