Although much is known of the impact of systematic reading instruction on writing performance and of systematic writing instruction on reading comprehension, little is known regarding the reading-writing connection based on independent reading and writing. This systematic review identified 13 experimental studies published between 1970 and 2019 that purported to investigate the impact of independent reading on writing performance and of independent writing on reading comprehension. Findings conclusively suggest that independent reading enhances the overall quality of narrative and descriptive writing and increases output, mechanics, spelling accuracy, content, grammatical accuracy, and text organization. However, independent reading failed to enhance vocabulary ratio, length of T-units and sentences, and sentence structure at a statistically significant level. Moreover, independent writing improves literal reading comprehension for beginning, low-performing, and at-risk students, and improves literal and inferential reading comprehension for normally achieving students. The findings suggest that the writing-to-reading connection may be moderated by the level of language proficiency. Discussion, limitations, and directions for future research are provided.