This paper combines dynamic social choice and strategic experimentation to study the following question: How does a society, a committee, or, more generally, a group of individuals with potentially heterogeneous preferences, experiment with new opportunities? Each voter recognizes that, during experimentation, other voters also learn about their preferences. As a result, pivotal voters today are biased against experimentation because it reduces their likelihood of remaining pivotal. This phenomenon reduces equilibrium experimentation below the socially efficient level, and may even result in a negative option value of experimentation. However, one can restore efficiency by designing a voting rule that depends deterministically on time. Another main result is that even when payoffs of a reform are independently distributed across the population, good news about any individual's payoff increases other individuals' incentives to experiment with that reform, due to a positive voting externality. Copyright 2010 The Econometric Society.