To probe the limits of attention raising through form-focused instruction, second-language research must adapt to the needs of a technologically driven learning environment. In this study, we used a randomized control design to investigate the effect of captioned media on the learning of vocabulary and grammar in L2 Spanish (n = 369 learners). Through four data-collection sessions, participants were presented with a grammar-lesson video and a multimodal video with one of three captioning formats: textually enhanced target vocabulary, textually enhanced target grammar, or no captioning. Results show strong immediate effects of captioning on target vocabulary, with additional effects of captioning on some, but not all, target-grammar structures. The findings demonstrate that (a) the learning of some grammatical structures is more conducive to captioning than others, and (b) there is space for future investigation into the factors that may influence the effectiveness of multimodal interventions, such as prior knowledge or frequency of use.