A surprisingly large number of lottery prizes go unclaimed every year. This leads us to suspect that what people bet on is not only money, but also good mood. We conducted three studies to explain, from an emotional perspective, why people play lottery games. We first conducted two survey studies to assess mood state reported by online (Study 1a) and offline lottery buyers (Study 1b) at different stages of lottery play. The results revealed that participants’ highest mood appeared before knowing (...) whether they had won. In Study 2, we manipulated the means of reward (lottery tickets vs. cash) and compared participants’ mood changes at different stages of a rewards game in the laboratory. We found the following: first, lottery group participants were generally in a better mood; second, 42% of lottery group participants did not come to the laboratory to collect scratch cards; and third, lottery group participants took more time to return to the laboratory to check their tickets than participants in the cash group. In Study 3, we examined whether priming good or bad mood could influence participants’ preferences for cash versus lottery tickets. The results revealed that participants who were primed for poor mood had a higher preference for lottery tickets compared with their good mood counterparts. These findings suggest that what our participants sought in lottery play was not only money, but improved mood. (shrink)