In this paper, we present a study which describes and compares the production of lexical errors at the end of two important educational stages: Primary and the compulsory years of Secondary education.Identifying the most frequent lexical error types at each acquisition stage can be very insightful in distinguishing among proficiency levels and establishing lexical benchmarks.Our results show a slight decrease in lexical error production, only significant for direct L1 borrowings.However, they also reveal an increase of misselections and coinages at higher levels.Furthermore, we observed presence of fossilized errors and errors in constructions.Results are interpreted in light of previous research-related literature concerning the evolution of lexical errors along proficiency levels.Finally, some pedagogical implications are suggested to improve the lexical production of Primary and Secondary school learners in order to prevent and remedy the lexical errors they committed.