Defining Fractional Leadership for the Sustainability Profession
December 3, 2025
Fractional… It’s a term that has become a buzzword for part-time executive leadership across finance, marketing, operations, and beyond. But what does “fractional” mean in the context of sustainability, and why are more companies embracing it?
At its core, “fractional” simply refers to being a fraction of a whole, or in this case, a specific role. In a business context, it refers to a senior leader who contributes a portion of their time to a company—offering deep expertise and strategic vision without the commitment or cost of a full-time hire.
How does this apply to sustainability?
If you’re familiar with the role of a CSO (Chief Sustainability Officer) you know that sustainability isn’t just about ‘doing good’ - it’s about strengthening long-term business value. An effective sustainability leader embeds sustainability into core operations and decision-making. This integrated kind of leadership can build resilient supply chains, reduce regulatory and reputational risk, meet customer requirements, attract investors and talent, and unlock innovation across the organization. Yet, many businesses aren’t ready, or resourced, for a full-time CSO. What they do need is access to senior-level sustainability leadership on a part-time basis: someone who can develop strategy, engage teams, and implement sustainability programs effectively.
Enter the Fractional Sustainability Leader (FSL)
An FSL is an embedded, senior-level sustainability professional who works in a part-time capacity while developing and executing a company’s sustainability strategy, engaging key stakeholders, and driving measurable results.
At the core of their role, an FSL is a hands-on leader who makes sustainability operational.
Seeing the need to define fractional, and this role, more clearly, the Fractional Sustainability Leaders Collective (FSL Collective) has established a definition in hopes that it becomes a standard for the sustainability profession. Building on the framework of the Fractional Leadership Alliance, the below graphic illustrates how fractional leadership compares to other engagement models and how a Fractional Sustainability Leader uniquely complements other forms of support.
In the era of the gig economy, it’s easy to mistake fractional leadership as consulting rebranded. But an FSL is not an outside advisor or arm’s length service provider—they are embedded within the business, working alongside internal teams to provide hands-on leadership and execution. The work model may be fractional, but an FSL brings the same dedication, expertise, and impact as a full-time in-house sustainability leader, ensuring sustainability becomes an operational advantage rather than just an initiative.
Why not just hire a CSO, or make this a junior level full-time role?
Not every company needs—or is ready for—a C-suite sustainability executive. Many businesses benefit greatly from the experience of a Director- or Vice President-level leader who can establish and scale sustainability programs effectively. An FSL engagement gives businesses access to senior-level professionals on a part-time basis, with a model that can scale with their needs. And unlike a junior hire, an FSL brings leadership experience paired with deep subject matter knowledge, allowing them to navigate complex stakeholder dynamics, lead cross-functional initiatives, and drive strategic impact from day one.
An FSL can work alongside an existing sustainability team to fill gaps, build internal capacity, and strengthen decision-making and execution. Rather than restructuring or displacing staff, a FSL enhances what’s already in place—bringing clarity, experience, and hands-on support for as long as needed.
Fractional Sustainability Leadership gives organizations the flexibility to lead with purpose, while scaling expertise to match their stage of growth and maturity. Whether you’re building your first roadmap or strengthening an established program, an FSL can help turn ideas and ambition into action.
View the FSL Collective’s definition of Fractional Sustainability Leadership, along with guidance on structuring an engagement and common FAQs about fractional, on our website.
