Coastal succulent scrub of Baja California is being fragmented and replaced by agriculture, residential, recreational, commercial, and industrial land uses. This study evaluated fragmentation effects of a residential-recreational development. The site was a mosaic of native coastal succulent scrub (CSS) in a matrix of introduced grasslands and tourism infrastructure. Comparisons were made among extensive areas of mature or old CSS and smaller patches, which were either recently fragmented in a golf course or fragmented more than 20 years ago in a residential area. Total plant species richness was 108 species. New fragments exhibited the highest floristic richness due to invasion by opportunistic species. The number of CSS species increased with patch size. There were differences in flora among seasons due to spring annuals. In contrast, cover by native perennials was similar among all conditions and MANOVA results showed that only the variables related to origin (natives and nonnatives) were significant. This means that neither life form nor fragment type was related to the species number. Our study reflects the potential to preserve coastal sage scrub patches within an urbanized area.