This study investigates caption-reading behavior by foreign language (L2) learners and, through eye-tracking methodology, explores the extent to which the relationship between the native and target language affects that behavior. Second-year (4th semester) English-speaking learners of Arabic, Chinese, Russian, and Spanish watched 2 videos differing in content familiarity, each dubbed and captioned in the target language. Results indicated that time spent on captions differed significantly by language: Arabic learners spent more time on captions than learners of Spanish and Russian. A significant interaction between language and content familiarity occurred: Chinese learners spent less time on captions in the unfamiliar content video than the familiar, while others spent comparable times on each. Based on dual-processing and cognitive load theories, we posit that the Chinese learners experienced a split-attention effect when verbal processing was difficult and that, overall, captioning benefits during the 4th semester of language learning are constrained by L2 differences, including differences in script, vocabulary knowledge, concomitant L2 proficiency, and instructional methods. Results are triangulated with qualitative findings from interviews. (Contains 4 tables, 2 figures, and 9 notes.)