An ongoing survey of the vascular flora of the Marietta Sand Prairie Preserve in Marshall County, Iowa, was begun in the 2022 growing season. Originally purchased for protection from agriculture in 1983, the Marietta Sand Prairie Preserve initially consisted of a “postage stamp” of just 6.9 ha (17 acres) of remnant sand prairie and wet sedge meadow that was dedicated as a biological and geological Iowa state preserve the following year. Marietta Sand Prairie was expanded in 2006 with an addition of about 85.8 ha (212 acres), which, although publicly owned, is not designated as part of the state preserve. The addition contains sand prairie habitat as well as restored prairie on less sandy soil, more recently abandoned agricultural fields previously planted with Glycine max (soybean) and Sorghum bicolor (sorghum or great millet), and several wetlands, including unusual small hillside fens. Sand prairie habitat is considered globally rare; about 47 ha of this habitat type are protected in state preserves in Iowa, where over 99% of land has been converted to agriculture or otherwise developed. The existence of the sand prairie habitat is dependent upon disturbance, and management techniques such as burning are undertaken by the Marshall County Conservation Board on a regular basis to clear woody debris. As with many state preserves in Iowa, Marietta Sand Prairie is also open to hunting, hiking, and birdwatching. In the first year of this study, approximately 280 different vascular plant species, subspecies, or varieties representing 195 genera and 78 families were collected and vouchered at the Ada Hayden Herbarium at Iowa State University. Several species of interest were found within the original 6.9 ha remnant, including Carex conoidea and Platanthera clavellata, which are listed as species of special concern in Iowa, and Botrychium tenebrosum, a currently unevaluated species that is likely rare in the state. This largely student-led project will continue through the 2023 and 2024 growing seasons and is expected to locate many additional species in the preserve, including some recorded in previous work in 2014 and 2015 by plant ecologist Scott Zager. A comparison of species composition of 27 prairies protected in the Iowa State Preserves system will be presented alongside the species composition of Marietta Sand Prairie Preserve. The goal of this project is to not just document vascular plant species presence, including the addition of new and potentially invasive species and possible loss of plants previously collected at the site that we can no longer locate, but to also report these findings to land managers and other stakeholders to help inform management decisions at this dynamic, multi-use site.