Diadema antillarum was once ubiquitous in the Caribbean, but mass mortality in 1983-84 reduced its numbers by >97%. We measured Diadema abundance on back reefs and patch reefs that have been well studied for >25 years. From June 2000 to June 2001, populations on back reefs have increased >100% (June 2001 mean densities 0.004-0.368/m2), while patch reef populations increased >350% (June 2001 densities 0.236-0.516/m2). Populations are dominated by small urchins, suggesting high recent recruitment. Increased Diadema densities appear to be affecting macroalgae abundance. The general spatio-temporal pattern of recovery around St. Croix seems to be following that of the die-off, suggesting that the same oceanographic features that spread Diadema's pathogen are now carrying urchin larvae.