The purpose of this experimental study was to investigate the effects of textual and visual annotations on Spanish listening comprehension and vocabulary acquisition in the context of an online multimedia listening activity. 95 students who were enrolled in different sections of first year Spanish classes at a community college and a large southwestern university were randomly assigned to one of four versions of an online multimedia listening activity that contained textual and visual annotations of several key words. Students then took a comprehension and vocabulary posttest and a survey to measure cognitive load and general attitudes towards the program. Results indicated that textual annotations had a significant positive effect on listening comprehension and that visual annotations had a significant positive effect on how successful students felt. No statistically significant differences were found for other variables. Participants also reported positive attitudes towards vocabulary annotations and expressed a desire to see more annotations during multimedia listening activities of this type. These findings provide further evidence of the impact that multimedia may have on language acquisition. These findings have implications for multimedia design and for future research. Language listening activities should include a variety of vocabulary annotations that may help students to understand what they hear and to help them learn new vocabulary. Further research is needed outside of the laboratory, in the online and increasingly-mobile language learning environment in order to align the research with the environment in which many students currently study. The incorporation of motivation into multimedia learning theory and cognitive load should be explored, as well as new measures of cognitive load.