The general aim of this research is to assess the level of sustainability of the soy-growing municipalities in the state of Mato Grosso. Specifically, it sought to analyze the process of expansion of soybean cultivation in Mato Grosso and, based on its specificities, to develop an indicator of the level of sustainability of soybean-growing municipalities. To this end, the degree of importance of the determinants of municipal sustainability and the influences of the soy production agglomeration on the municipalities of Mato Grosso were identified. To this end, the methodological procedures used were the proposal of the Municipal Sustainability Indicator for Soy Growing Municipalities (ISMS), the factor analysis technique and cluster analysis. The conclusion is that the expansion of soybean production in Mato Grosso has been taking place in areas with greater negative externalities, without the counterpart of an increase in the level of local development, which requires a reassessment of the soybean production structure in the municipalities of Mato Grosso and the reversal of public policies that encourage the process of agricultural expansion in the regions of the Amazon ecosystems and the preservation of the Cerrado.