Public-private partnership (PPP) has been positioned as a relevant contracting method for developing large-scale infrastructure projects, which entail potentially high-magnitude negative impacts on the environment. The effectiveness of their Environmental Impact Assessment (EIA) is crucial to achieving sustainable development of these large-scale infrastructure projects. To unravel the drivers for the EIA effectiveness and the multiple combinations built by the complexity of these drivers, this paper analyzes 28 road PPP projects from Colombia employing a fuzzy-set qualitative comparative analysis (fsQCA) approach. This paper decodes conjectural causal links between specific conditions grouped in superordinate clusters (i.e., consultants' capability, project features, and communities' participation) and EIA effectiveness dimensions (i.e., normative, procedural, substantive, and transactive). Findings revealed that no single combination of causal conditions ensures multidimensional EIA effectiveness. This study demonstrated that EIA effectiveness relies significantly on the integration of specific features of three external stakeholders: consultants, nonpreferred proponents, and communities. This study constitutes the first empirical multidimensional identification of the combination of conditions that generate EIA effectiveness in road PPPs.