Seabeach amaranth (Amaranthus pumilus) is a federally threatened plant species that was once prevalent on beaches of the U.S. mid-Atlantic coast. To re-establish a population at Assateague Island National Seashore (ASIS), seabeach amaranth cultivars were planted by ASIS natural resources staff for three growing seasons from 1999 to 2001 and have been monitored since 2001. Characteristics of favorable seabeach amaranth locations were assessed by sampling barrier island and habitat characteristics at sites where plants are and are not observed in 2008, 2010, and 2014. These data can then be used to develop probabilistic models that provide maps of habitat suitability to identify high-priority areas for amaranth protection. The modeling effort also helps to inform management decisions that are most likely to result in the protection of a long-term sustainable population.