This study delves into the intricacies of second-language sentence comprehension, investigating the impact of psycholinguistic variables. An online sentence comprehension task engaged 100 proficient English speakers with intermediate Spanish proficiency, integrating eye-tracking technology. Assessing sentence complexity, word order, lexical ambiguity, and working memory, the findings highlight higher accuracy in simple declarative sentences, while non-canonical word orders led to significantly prolonged response times. Lexical ambiguity correlated with increased error rates, yet superior working memory capacities were associated with enhanced processing efficiency. The research underscores the necessity for nuanced language instruction, emphasizing metacognitive strategies to address challenges posed by sentence complexity and ambiguity. Despite limitations in sample size and controlled settings, this study lays a foundational framework for future cognitive investigations into second-language sentence comprehension.