A series of experiments illustrate that relaxing short-selling constraints lowers prices in experimental asset markets, but does not induce prices to track fundamentals. We argue that prices in experimental asset markets are influenced by restrictions on short-selling capacity and limits on the cash available for purchases. Restrictions on short sales in the form of cash reserve requirements and quantity limits on short positions behave in a similar manner. A simulation model, based on DeLong et al. (1990), generates average price patterns that are similar to the observed data.