This study investigated the reading comprehension scores of students with reading and language difficulties after reading a passage with and without text-to-speech (TTS). Students, ages 8 to 12 years, read five passages under the following conditions: (1) "silent read;" (2) "read aloud;" (3) "listen only;" (4) "TTS with no highlighting;" and (5) "TTS with highlighting." Students answered multiple-choice comprehension questions following each condition. Mixed ANOVAs were performed to determine whether "TTS" improved reading comprehension. "TTS" significantly improved comprehension in comparison to "no TTS," and specifically, "TTS with no highlighting" and "TTS with highlighting" resulted in significantly higher comprehension scores compared to "silent read." No other significant differences were found across conditions including between the presentational features of TTS, specifically "TTS with no highlighting" and "TTS with highlighting" conditions. Students were grouped as dyslexia only or reading and language impairment based on their test results. Findings suggested that students with dyslexia only scored significantly higher on reading comprehension questions in all reading conditions and derived significantly more benefit in reading comprehension from "TTS" and the "listen only" condition compared to students with Reading and Language Impairment. Overall, TTS may be a helpful tool for supporting the reading comprehension of students with reading and language difficulties, particularly for students with dyslexia only; however, further studies are needed to explore the benefits of TTS' presentational features such as highlighting with students with reading and language difficulties.