With students' study load becoming increasingly controversial around the world, we investigated whether "less can be more" regarding the relationship between study load and science achievement (i.e., lighter study load, higher science achievement). Using data from the 2016 (Chinese) Program for Regional Assessment of Basic Education Quality (N = 40,536 students under 946 science teachers within 118 schools), we constructed seven measures of study load. We developed multiple membership multilevel models to accommodate students being taught by multiple science teachers. After adjustment for student, teacher, and school characteristics, six measure did not indicate any statistically significant relationship between study load and science achievement, with one indicating a statistically significant but negative relationship, leading us to conclude that heavier study load was not associated with higher science achievement. Meanwhile, some school climate variables could function as moderators of the relationship with academic pressure and parental involvement as the highlights. Under the reduction in these variables, lighter study load began to associate with higher science achievement.