Society uses the following mechanism to decide on the supply of a public good. Each agent canchoose whether or not to contribute to the good. Contributions are collected, and the good issupplied whenever total contributions exceed a threshold. We study the case where the publicgood is excludable, agents have a common value, and each agent receives a private signal aboutthe common value. We study how such collective decisions perform in terms of informationaggregation, social efficiency, and market traction.