Invasion of Alliaria petiolata (garlic mustard) has become increasingly problematic, as it has disrupted the native ecosystem of the forest understory throughout most of the United States. A key element of garlic mustard invasion is the production of two compounds that have been shown to be inhibitory at relatively low concentrations, allyl-isothiocyanate (AITC) and benzyl-isothiocyanate (BITC). The current study utilizes Minimum Inhibitory Concentration tests to assess the effect of AITC, BITC, and AITC and BITC in combination on the soil microbial community across a gradient of invasion severity: from uninvaded, moderately invaded, and heavily invaded sites. It is hypothesized that prior history of garlic mustard invasion, chemical treatment, previous chemical exposure and chemical concentration will all influence microbial growth. Results showed that invasion history and chemical condition significantly influenced microbial growth for initially exposed trials, but only chemical condition influenced the growth of previously exposed trials. Microbial growth in initial trials was significantly higher than growth in previously exposed trials, and increasing chemical concentration correlated to decreased microbial growth. A better understanding of the relationship between garlic mustard and the general soil microbial community will enable the design of more efficient and site-specific evaluation and treatment techniques, as well as provide insights into the impact that invasion has on ecosystem processes.