This paper presents an experimental study of dynamic indefinite horizon R&D races with uncertainty and multiple prizes. The theoretical predictions are highly sensitive: small parameter changes determine whether technological competition is sustained over time or converges into a market structure with an entrenched leadership and lower aggregate R&D research. The subjects' strategies are far less sensitive. In three out of four treatments (with the exception being a control treatment), the R&D races tend to converge to entrenched leadership. Investment is highest when rivals are close, and there is evidence of average over-investment.