We investigate experimentally whether the endowment of potential contributors changes outcomes in threshold public-good games. We find that the variance in contributions is significantly reduced for low and high levels of endowment in comparison with an intermediate level of endowment. This difference emerges with experience. Evidence on whether the level of endowment influences the success rate at providing public goods is more mixed. We provide, however, a measure of endowment size that correlates with success rate. Our interpretation suggests that people find it hardest to coordinate on the provision of threshold public goods when endowments are of intermediate size. By intermediate we mean that the endowment is small enough that people need to contribute relatively a lot to fund the good, but also large enough that no one person is critical in providing the good.