This series of experiments investigated whether the detrimental effects of unattended speech that have been obtained in short-term memory tasks would be obtained in reading comprehension. Such effects would be expected if reading comprehension depends on the maintenance of phonological information in short-term memory. The first three experiments demonstrated that unattended speech but not music interfered with reading comprehension while unattended music had a greater interfering effect than speech on a music identification task. Experiments 4 and 5 showed that the detrimental effect of the speech backgrounds on reading was due to their semantic rather than their phonological properties. The failure to find a phonological interference effect argues against a role for phonological short-term memory in reading comprehension.