There are several arguments why the economic analysis of gambling seems to be very interesting. Gambling is a very important economic industry from which either local or national governments obtain resources due to some sort of fiscal imposition on gambling participation. On the other hand, the consumption of gambling seems to violate the premises of economic theory (risk aversion, maximizing and rational conduct). The empirical literature on this field has tried to answer several questions that might be summarized as follows: Who does gamble? Why do people gamble? And, how do game features, such as the rules or the prize structure, affect the demand for gambling? This thesis tries to shed more light on the questions identified above, focusing on the particular case of state-operated lotteries and football pools in Spain. Specifically, we are interested in examining what aspects drive gamblers' participation in Spanish lottery markets and spending on lotteries, focusing on network externalities in consumer spending on closely related lottery goods. Next, we study the demand for a particular game, paying attention to the factors that explain why individuals bet, especially, those that refer to the design of the game and the structure of prizes. Finally, the analysis of the main economic determinants of demand for gambling is extended to football pools as a particular form of sports gambling. In addition to these empirical exercises, this study contributes to the economics of gambling by briefly reviewing the theoretical work and empirical highlights from the previous analysis of the demand for lottery.