This paper reports results from a laboratory experiment comparing voting behavior and decision making efficiency in standing and ad hoc committees, where decisions are made by unanimity rule. We also compare sequential and simultaneous (secret ballot) voting procedures. The data are remarkably consistent across treatments, in both qualitative (comparative statics) and quantitative terms. The different procedures and the ad hoc or standing nature of the committees generally do not seem to lead to the selection of different equilibria, with the exception of some evidence of bandwagon effects in the sequential procedure.