Student motivation may have significant influences on essential academic outcomes. However, students' motivation may decline as they grow older. This study examined six motivation constructs (self-efficacy, interest, mastery goal orientation, engagement, avoidance coping, and effort withdrawal) of students from 78 schools in Singapore (N = 4214) in learning English. Using a large and diverse sample of primary 5 (5th grade) and secondary 3 (9th grade) students, grade and gender differences in these constructs were examined. Applying a MIMIC approach to structural equation modeling, the paths from grade and gender as well as the grade x gender interaction variable were found to be significant. That is, (a) the scores for self-efficacy, interest, mastery goal orientation, and engagement tended to be lower whereas avoidance coping and effort withdrawal tended to be higher for the secondary students, (b) boys tended to have lower scores; and (c) the gap in motivation between primary and secondary tended to be greater for girls. Since motivation may have important influences on subsequent learning outcomes, we need to seriously consider the implications of these grade- and gender-related patterns and pay attention particularly to boys in primary schools and girls in secondary schools. (Contains 4 tables and 1 figure.)