It has been proposed that impact assessment can meet ambitionsto prove and improve social and environmental performance. Thisbecomes relevant in social entrepreneurship, with its mission tocreate social value. As impact assessment appears complex andresource-intensive for nascent or very small organisations, thispaper identifies which dimensions are crucial for credible impactassessment and examines circumstances for their application. Wepropose a staged approach to impact assessment which complieswith established concepts and practices while still allowing flexibleapplication in relation to entrepreneurial ambitions and organisationalcircumstances. Our approach is illustrated through a multiplecase study.