The popularisation of the Social Licence to Operate in measuring the acceptance of mining projects has stimulated the development of critical studies that question how the practical use of this management model has favoured the reduction of risks for the business without generating gains for the community. We propose in this article that the integration of Social Impact Assessment in Social Licence to Operate contributes to deepening the understanding of the social acceptance of mineral projects, especially in contexts of vulnerability. The objective of this research is to discuss the social acceptance of mining projects integrating the results of Social Licence to Operate and Social Impact Assessment approaches applied in a mineral project in the Brazilian Amazon. The methodological procedures of this research included document analysis, survey application, and interviews. The results show that Social Impact Assessment, by enabling the understanding of the local context and social impacts, serves as a complementary instrument to Social Licence to Operate measurement models. By giving voice to the local community, the use of Social Impact Assessment shows means that could effectively contribute to local development, based on actions involving the company and local government in order to act in the most sensitive areas that impact the community, such as its economic, social, environmental, and cultural challenges. Les recentes tragedies minieres au Bresil remettent en question le discours et la pratique du modele LSO dans des contextes de vulnerabilite sociale. La recherche universitaire defend l'integration de l'EIS dans la LSO afin d'attenuer les impacts negatifs et d'accroitre les benefices des projets miniers pour la communaute locale. Nous proposons et testons un modele permettant de mesurer les facteurs critiques de l'acceptation sociale afin d'evaluer la LSO dans la municipalite de Parauapebas/PA, en Amazonie bresilienne, dans le cas de l'une des plus grandes reserves minieres du monde. Nous articulons les resultats du modele et les resultats de l'EIS participative qui a ete developpee simultanement sur le territoire de Parauapebas afin de mieux comprendre les impacts sociaux et le manque de confiance qui en resulte. Las recientes tragedias mineras en Brasil cuestionan el discurso y la practica del modelo LSO en contextos de vulnerabilidad social. La investigacion academica defiende la integracion de la EIS en los LSO para mitigar los impactos negativos de los proyectos mineros y ampliar sus beneficios para la comunidad local. Proponemos y probamos un modelo de medicion de los factores criticos de la Aceptacion Social para evaluar la LSO en el municipio de Parauapebas/PA, en la Amazonia brasilena, en el caso de una de las mayores reservas mineras del mundo. Articulamos los resultados del modelo y los resultados de la EIS participativa desarrollada a la vez en el territorio de Parauapebas para lograr una mejor comprension de los impactos sociales y de la consiguiente falta de confianza.