In recent years, the issue of sustainability has assumed great importance in every field, including noise mitigation measures, and interested stakeholders have found themselves struggling with still evolving and uncertain techniques to evaluate the related social, economic and environmental aspects. Indeed, the sustainability assessment can be accomplished with many different methods and countless indicators. To clarify the problem and identify suitable methodologies to assess the sustainability of noise mitigation solutions for roads, the Italian PIARC committee TC 3.4.2 has undertaken an in-depth study on the most ascertained techniques, from Life Cycle Sustainability Assessment to the more recent Envision protocol. This study has involved a broad and focused effort to define the meaning of sustainability, from the perspective of infrastructure managers, users and the general population. Criteria and indicators to describe the performance of noise mitigation solutions have been identified and a general procedure for assessing the sustainability of noise mitigation measures has been defined. The selected method and indicators have then been applied to two case studies to test their applicability and reliability: the first one in an urban setting and the other one in a suburban environment. In this paper, the main outcomes of this study are reported.