Securing leadership support and funding for sustainability initiatives requires compelling business cases that align the environmental benefits with financial and strategic value. This presentation will provide practical guidance on crafting persuasive business cases for sustainability projects in pharmaceutical manufacturing. Drawing on the work of the Circular Economy sub-committee of the ISPE Sustainability community of practice (CoP) on this topic, we outline key elements that drive success, including lifecycle cost analysis, risk mitigation, regulatory alignment, and stakeholder engagement. Attendees will gain insights into quantifying sustainability benefits, integrating circular economy principles, and addressing common objections from decision-makers. Case studies will illustrate how well-crafted proposals can translate sustainability goals into actionable investments. Whether advocating for energy efficiency, waste reduction, or green chemistry initiatives, participants will leave with actionable strategies to strengthen their business cases and advance sustainability within their organizations.