Many endangered species are distributed in narrow geographic ranges, often at severe risk of extinction. Ecological niche modeling can be used to identify suitable areas, which can be surveyed to detect additional populations. We combined remotely sensed data (Normalized Difference Vegetation Index) and field sampling to increase distributional knowledge of the species and improve understanding of its conservation status. We identified numerous new sites for a rare plant (Dianthus pseudocrinitus) and tested model-based predictions of its full geographic distribution. Using only eight occurrences, we developed initial models, which guided detailed field sampling: 11 new sites were identified, but models were unable to predict better than random expectations. A second round of models did show significant predictive ability and pointed to a broader geographic and environmental distribution of the species. As a consequence, the conservation status of the species should be upgraded from Critically Endangered to Endangered. We identified six protected areas (Golestan, Ghorkhoud, Miandasht, Salouk, Sarani, Sarigol) that likely hold populations of this species; one area adjacent to Ghorkhoud Protected Area, if protected, would protect the best-known populations of the species. Our results highlight the importance of combining modeling with field sampling in characterizing distributions of rare and endangered species.