These are data sets and data analysis files in R for an eye movement experiment using the boundary paradigm to investigate parafoveal processing in Chinese by young and older adult readers. Participants read sentences containing two-character target words with high or low contextual predictability. Before the reader's gaze crossed an invisible boundary, each target was shown normally (a valid preview) or its characters were either transposed or replaced by unrelated characters, creating invalid previews that reverted to normal once the reader's gaze crossed the boundary. Transposed-character effects were similar for both groups suggesting that this intriguing aspect of parafoveal processing is preserved in older readers.