The Understanding Social Impact Measurement Toolkit, developed by Social Enterprise Northern Ireland in partnership with the Department for the Economy, is a practical and accessible guide designed to help social enterprises understand, plan and measure their social impact. The toolkit takes an interactive, step-by-step approach, guiding organisations through clarifying purpose, developing a Theory of Change, identifying priority outcomes and building a simple, meaningful impact measurement framework. It combines practical exercises, planning tools and real-world examples to support organisations in measuring what matters and using impact data to improve practice, communicate value and support funding and investment decisions.