Event-related potentials (ERPs) have become widespread in second language acquisition (SLA) research and a growing body of literature has been produced in recent years. We surveyed 61 SLA papers that use ERPs to study L2 sentence processing in healthy late learners. Our main aim was to provide a critical summary of findings from the decade 2010-2020. The qualitative review reveals that proficiency plays a major role in determining ERP components, but its effect is modulated by language similarity and individual differences. The statistical analysis (a multinomial logistic regression) suggests that ERP components are uniquely predicted by learners' proficiency level and the linguistic phenomenon at issue, while no effect of language distance is found. We also made a cursive methodological overview, which evidences several gaps in the literature and raises some concerns on the way proficiency is factorized across studies.