This study addresses a critical gap in second language acquisition (SLA) research by investigating academic vocabulary knowledge in Spanish L2 learners. Despite extensive research on academic vocabulary in English, Spanish remains underexplored, particularly regarding its distinctiveness from general vocabulary and its cognitive processing demands. The project pursues four interdisciplinary objectives: (1) identifying academic vocabulary in Spanish Humanities through corpus analysis, (2) developing and validating the Academic Vocabulary Knowledge in Spanish L2 Test (AViSpa), the first empirically grounded assessment tool for Spanish L2 learners, (3) examining real-time cognitive processing of academic texts using eye-tracking technology to quantify lexical frequency and coverage effects, and (4) correlating cognitive effort with language proficiency, general vocabulary knowledge, and reading comprehension to propose an integrated model of L2 academic literacy. By combining corpus linguistics, psycholinguistics, and SLA frameworks, this research advances theoretical debates on lexical acquisition, cognitive load, and register acquisition in Spanish. Additionally, this project bridges the gap between research and practice, offering evidence-based strategies to enhance academic language proficiency in higher education contexts.