The present study investigates how second language (L2) learners' proficiency and the similarity between their L1 and L2 influence L2 morphosyntactic processing. Additionally, it examines how these two factors modulate learners' sensitivity to syntactic and semantic predictive information. Specifically, this study uses event-related potentials (ERPs) to examine the processing of gender agreement in French by French natives, advanced learners, and intermediate learners with gendered L1 (German) and ungendered L1 (Mandarin). To achieve this, participants' EEG is measured while they read grammatical and ungrammatical French sentences with and without semantic gender, as well as with and without syntactic gender predictive information. The study then compares participants' ERPs on experimental items across different conditions. By investigating how semantic and syntactic predictive information enhance gender agreement in learners with different L1 backgrounds and proficiency levels, the study aims to gain a better understanding of the underlying reasons for the difficulties in L2 gender agreement.