This extension study investigates the relationship between self-regulated learning (SRL) strategies and first language (L1) Chinese and second language (L2) English reading test performance among 190 primary six students in mainland China, building upon the findings by Tse et al. (2022). Confirmatory factor analysis confirmed the acceptable construct validity of the SRL strategy use questionnaire used by Tse et al. (2022). Structural equation modeling was then conducted to examine the direct relationships between variables. The results reveal a direct and positive relationship between L1 Chinese planning strategies and L2 English planning strategies, as well as between L1 Chinese monitoring strategies and L2 English monitoring strategies. Furthermore, L1 Chinese SRL strategies directly and positively predicted L1 Chinese reading test performance, while L2 English SRL strategies had a direct and positive effect on L2 English reading test performance. However, L1 Chinese SRL strategies did not have a significant predictive effect on L2 English reading test performance. Additionally, the performance on the L1 Chinese reading test had no significant effect on L2 English reading test performance. These findings underscore the importance of integrating L1 Chinese and L2 English curricula in mainland China and fostering communication and collaboration between L1 Chinese and L2 English teachers. Additionally, the study suggests several directions for further research in this area. [The volume (36) on the .pdf is incorrect. The correct volume is 37.]