This study compares L2 classroom assessment practices related to learning motivation in a high-performing grammar school and middle-range regular school to find the characteristics of L2 classroom assessment that promote learning motivation. First, we observed how four L2 teachers assessed eight seventh-grade classes at the two schools (four classes per school). Then, we administered questionnaires to the students in these eight classes to investigate the correlation between classroom assessment and learning motivation. Finally, we conducted semi-structured interviews with the four teachers (each teacher in charge of two classes) and 10 randomly stratified students to interpret such a relationship. Quantitative data were projected into SPSS 25 for analysis, and qualitative data were analyzed thematically. The results showed that it was not the frequency but the characteristics of assessment that fostered learning motivation. The results suggest including assessment techniques to enhance learning motivation in Vietnamese L2 teacher education programs.