In the volume of essays on Gilbert Ryle published in 1970 by George Pitcher and Oscar Wood, there is a paper by Peter Strawson on categories. In my contribution to this new volume on Ryle, I go through some now well-recognised difficulties with Ryle's own treatment of categories, and in particular of category mistakes. I then consider some general problems that beset the efforts of others to do better, before turning to Strawson's suggestions, which as far as I can discover have never been discussed in print. These suggestions have obvious merits, but I end by arguing that they are less than fully successful.