Illinois is home to approximately 2,107 native plant species of which about 16% are listed as threatened or endangered (T & E). In addition to the common threats associated with the decline of these species, climate change is a rapidly emerging threat. Climate predictions for Illinois have estimated that summer temperatures will resemble present-day summers in Texas by mid- to late-century, while precipitation patterns are less predictable. Using NatureServe's Climate Change Vulnerability Index (CCVI) tool we evaluated the climate change vulnerability for all 331 of Illinois T & E plant species. Overall, we found that over 80% are vulnerable to climate change. Barriers to migration are a leading factor associated with vulnerability in Illinois, where 97% of listed species are affected by anthropogenic barriers and 24% are affected by natural barriers. The sensitivity of species to changes in temperature, precipitation, and hydrology are also associated with vulnerability. The CCVI score was associated with most of the dozen or so other factors incorporated in the tool, though to a lesser degree. This study provides insights into the most vulnerable plant species in Illinois and provides much needed information to land managers, policy makers, and researchers. By highlighting which T & E species are most vulnerable to climate change, and what factors are most responsible for their vulnerability, this work will aid in prioritizing limited resources and developing adaptation strategies for them.