The self-generation effect refers to the finding that people’s memory for information tends to be better when they generate it themselves. Counterintuitively, when proofreading, this effect may make it more difficult to detect mistakes in one’s own writing than in others’ writing. We investigated the self-generation effect and sources of individual differences in proofreading performance in two eye-tracking experiments. Experiment 1 failed to reveal a self-generation effect. Experiment 2 used a studying manipulation to induce overfamiliarity for self-generated text, revealing a weak but non-significant self-generation effect. Overall, word errors (i.e., wrong words) were detected less often than non-word errors (i.e., misspellings), and function word errors were detected less often than content word errors. Fluid intelligence predicted proofreading performance, whereas reading comprehension, working memory capacity, processing speed, and indicators of miserly cognitive processing did not. Students who made more text fixations and spent more time proofreading detected more errors.