Survey research in the Global South traditionally requires large budgets and lengthy fieldwork, for which researchers hire local enumerators to conduct face-to-face surveys with respondents. However, much of the world’s population is now digitally accessible, offering an opportunity for researchers with limited budgets and those seeking to study settings where in-person contact is impossible, such as natural disasters, violent conflicts, and pandemics. In this paper, we evaluate whether Facebook advertising can be used to cost-effectively generate representative survey samples in the Global South. We introduce a framework for evaluating quality in Facebook survey samples, highlighting key trade-offs for researchers considering the platform. We then quota-sample respondents in two countries: Mexico (n=5,168) and Kenya (n=1,452) to evaluate how well these samples perform on a diverse set of survey indicators related to both internal and external validity. We find that while the Facebook platform can quickly and cheaply recruit respondents, these samples tend to be more male, more educated, and more urban than the overall national populations. Applying post-stratification weighting after oversampling key demographic variables ameliorates, but does not fully overcome, these initial sample imbalances. Our analysis demonstrates the considerable potential of Facebook advertisements to cost-effectively conduct research in diverse global settings.