This document discusses four models of social enterprises in Israel and implications for measuring their social impact. The four models are: 1) Business organizations, 2) Non-profits/NGOs, 3) Government agencies, and 4) Cooperatives. Each has a different ideological basis and emphasis for what and how to measure impact - business organizations focus on economic performance, non-profits on social outcomes, government agencies on budget impact, and cooperatives on solidarity. The document concludes that fully objective impact measures do not exist given the diversity of social enterprises, and that measurement is both a challenge and political process for demonstrating success while not being constrained by metrics.