This study examined the receptive vocabulary knowledge and lexical developmental patterns of the 3000 most frequent words among 953 university L2 learners of Spanish at different stages in their language studies, taking into consideration the effect of high school instruction on high-frequency vocabulary knowledge. Results confirm that even students who are enrolled in the most advanced courses in their program lack considerable knowledge of the 3000 most frequent words in their L2. Most vocabulary gains take place during the first semesters of instruction, and the learning of these words decreases substantially in intermediate and upper-division courses. Furthermore, high school instruction plays an essential role in developing a solid high-frequency vocabulary baseline but falls short in providing lexical learning beyond the first 1300 most frequent words. These results corroborate the need to implement a more lexically driven syllabus in the L2 Spanish language classroom to foster the learning of high-frequency words.