Testing your social impact hypothesis using the lean startup method involves four main steps. First, you build a minimum viable product (MVP) that can deliver your value proposition and measure your impact. You also define an experiment to test one of your key assumptions with a clear hypothesis and a success criterion. Second, you measure data from your experiment, such as customer feedback, user behavior, social outcomes, or revenue. Third, you analyze the data and compare it to your hypothesis and success criterion to determine if your experiment validated or invalidated your assumption and what insights you gained from it. Lastly, you decide whether to pivot or persevere based on your learning. Pivoting means changing your product, value proposition, or business model to better fit customer needs and social goals, while persevering means continuing with your current strategy and testing another assumption.