Addressing the complex nature of sustainable development requires project managers to adopt broader decision-making rationalities beyond conventional economic considerations. As key agents in translating sustainability goals into project actions, understanding their cognitive frameworks is essential. Yet, the rationalities guiding sustainability-oriented decisions remain underexplored in the literature. This study investigates the decision rationalities employed by project managers engaged in projects with social and/or environmental objectives. Eleven semi-structured interviews were conducted with project managers of sustainability-focused projects. Participants evaluated the adoption of forty structured statements reflecting four decision rationalities: bounded, instrumental, substantive, and communicative rationalities drawn from decision theory and sustainability literature. Findings indicate a predominant reliance on communicative and substantive rationalities, which emphasize stakeholder engagement, ethical reflection, and long-term environmental and social values. These rationalities appear particularly suited to the complexity of sustainability challenges. Nevertheless, aspects of instrumental rationality, particularly financial justification, remain salient. A recurring theme was the need to demonstrate financial viability to legitimize social or environmental benefits. This underscores the enduring dominance of economic reasoning, even within sustainability-oriented projects. By unpacking these rationalities, the study contributes to a deeper understanding of the decision-making logics shaping sustainable project management. The study identified how rationalities combine across individuals, revealing hybrid patterns of decision-making. This multidimensional approach provides a more nuanced understanding of how managers navigate the complexities of sustainability within their projects. Future research should extend empirical exploration across organizational contexts and support the development of tools that enable project managers to align sustainability values with decision-making processes, reinforcing project management’s potential as a driver of sustainable development.

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Decision rationality,project management,bounded rationlity,sustainability.

• Psychology - Social Sciences
• Economics and Business - Social Sciences