The study investigates immediate and delayed effects of different hypermedia glosses on incidental vocabulary learning and reading comprehension of advanced foreign language learners. Sixty-nine freshman TEFL students studying at a Turkish university were randomly assigned to three types of annotations: (a) definitions of words, (b) definitions coupled with associated pictures, and (c) definitions coupled with associated short videos. Subjects were asked to read an annotated text with the intention of comprehension. The data were collected through a vocabulary pre-test, a vocabulary post-test, a delayed vocabulary test as well as a reading comprehension test. In order to measure incidental vocabulary learning, subjects were not told that they were going to be given vocabulary tests. Results showed that the groups that had access to definitions along with both types of visuals had significantly higher vocabulary scores on both immediate and delayed posttests than the definition only group. However, no differences were observed on the reading comprehension test. Finally, the qualitative data revealed that hypermedia reading had positive impact on participants' attitudes towards foreign language reading and vocabulary learning.