In the context of sustainable densification of post-industrial European cities, urban wasteland regeneration projects offer an important potential of surfaces to recapture. Indeed, these projects can contribute concurrently to densify and revitalize existing built fabrics. Although numerous initiatives of this type can be observed, the integration of sustainability issues is in most cases partial or superficial. As a matter of fact, achieving the goals of sustainable development is not a spontaneous process. It depends upon a proactive search of global quality, integrated into the project dynamics, and a continuous assessment of the environmental, social and economic dimensions of sustainability adapted to the specificities of such projects. Based on these considerations, this paper introduces the indicator system entitled SIPRIUS, designed for the assessment of sustainability integrated into the dynamics of urban wasteland regeneration projects. First, the methodology that stands behind the development of SIPRIUS is exposed. Then, the paper presents the potential of SIPRIUS and its adequacy with concrete situations through a test application performed on a project underway in Neuchâtel (Switzerland). It reveals that an adapted and structured assessment approach truly contributes to integrating sustainability into urban wasteland regeneration projects.