There is a growing body of research on the role of linguistic features (LF) in comprehension and performance in science and math. Of particular interest is which LF facilitate or hinder comprehension. In this systematic review, we provide an overview of findings on LF at the word, sentence and text levels, on comprehension and performance in science and math. Our literature search revealed n = 40 articles included in this review. Overall, the role of LF in comprehension and performance in science and math is complex, with findings varying across the different LF. For each LF, we discuss the findings and uncover remaining questions. In the general discussion, we uncover strengths and weaknesses of previous research and discuss open questions before making eight recommendations and identifying tasks for future research aiming to understand the complex nature of LF.