Experimental entrepreneurship is often overlooked: experimentalists are less flamboyant than their conceptual peers, and their innovations arrive gradually and less conspicuously. Experimentalists work patiently to innovate, proceeding by trial and error in pursuit of ambitious but often imprecise goals. When individual experimental entrepreneurs are recognized, their successes are generally regarded as anomalous or idiosyncratic. But there is in fact a pattern of experimental entrepreneurship – of innovators gaining greater knowledge and judgment over the course of their careers, often arriving at their greatest achievements late in their lives. This paper examines the careers of a number of experimental innovators, including some of the most important entrepreneurs of the past century: their products vary widely, from hamburgers and sneakers to microloans and investment management, but all share the quality of perseverance coupled with a commitment to learning from experience.