Contemporary social exchange researchers have largely ignored how variations in the value of exchange affect power relations, concentrating instead on effects of the structure of exchange, particularly the size and shape of exchange networks. In this article, we show that value, when conceptualized and studied as a dimension of actors' alternative exchange relations, has strong and systematic effects on actors' use of power. Results of a laboratory experiment support our hypotheses, showing that an actor's power over another increases with the value of that actor's exchange with alternative partners. The effects of value on power use are comparable in strength to the effects of the availability of alternatives, and they are remarkably robust, holding for both negotiated and reciprocal forms of exchange and for networks in which the availability of alternative partners is both high and low.