This is a thesis about enhancing the management of sustainability opportunities during front-end development in infrastructure projects from the perspective of engineering consultancy firms. This thesis provides insights and guidance for project stakeholders to manage sustainability-related ambitions and ideas. Through empirical research within the Dutch infrastructure sector, this thesis has successfully identified the current landscape, key enablers and barriers to sustainability opportunity actualization. Combining these findings with theoretical analysis, the research develops the Sustainability Human-Centered Implementation Framework for Transition (SHIFT), a structured approach to improve the management and actualization of sustainability opportunities. The framework includes operational guidelines, validated through focus groups with highly experienced industry experts in the Netherlands. The implications of this research are to work towards a more sustainable construction environment and enhance the successful actualization of sustainability opportunities.