This study aims to evaluate the roles of social-emotional development, academic grit and subjective well-being in reading-writing motivation. Altogether 582 fourth-grade primary school students were sampled and invited to complete four different scales. The findings are: (1) Social-emotional development is correlated with reading-writing motivation, academic grit and subjective well-being. (2) Academic grit and subjective well-being play full mediating role in the relationship between social-emotional development and reading-writing motivation. (3) Although social-emotional development can be high in line the proposed model, the students with low academic grit and subjective well-being might have low reading-writing motivation. Practice or Policy: The results may provide a contribution for programs that could be prepared in relation to in these fields.