Proofreading a text for misspellings involves detecting spelling errors and then correcting those errors. We examined differences in spelling error detection and correction in adults as a function of type of spelling error. We modified student essays to include phonological (e.g., incredibul), orthographic (e.g., decisian), and morphological (e.g., extention) errors. Participants read and identified spelling errors in an unmarked copy of the essay. They were then given a second copy of the essay and asked to correct the marked spelling errors. Participants detected significantly more phonological errors than orthographic and morphological errors and detected morphological errors the least. There were no significant differences across error type in correction. These findings indicate that knowledge of how to correct an error may be sufficient for detection of phonological errors but is not always sufficient for detection of orthographic and morphological errors. Detection of morphological errors varied with spelling skill. Our results are consistent with the view that good spellers may have a larger memory for word-specific spellings and may have a greater familiarity with orthographic conventions than do average spellers.