This introductory chapter traces the development of population-based experiments and highlights some of their advantages over traditional experiments and surveys. There is a tendency to think about population-based survey experiments as simply a hybrid methodology that melds certain characteristics of surveys and experiments. But to say this tells nothing about which advantages and disadvantages of each methodology are inherited. The chapter argues that population-based survey experiments are instead more akin to an agricultural hybrid that produces something that was not present in either of the two original plants. To the extent that population-based survey experiments can be implemented with effective treatments and with the same degree of control over random assignment as in the lab, it is the only kind of research design capable of straightforwardly estimating population average treatment effects without complex statistical machinations.