External validity captures the extent to which inferences drawn from a given study's sample apply to a broader population or other target populations. Social scientists frequently invoke external validity as an ideal, but they rarely attempt to make rigorous, credible external validity inferences. In recent years, methodologically oriented scholars have advanced a flurry of work on various components of external validity, and this article reviews and systematizes many of those insights. We first clarify the core conceptual dimensions of external validity and introduce a simple formalization that demonstrates why external validity matters so critically. We then organize disparate arguments about how to address external validity by advancing three evaluative criteria: model utility, scope plausibility, and specification credibility. We conclude with a practical aspiration that scholars supplement existing reporting standards to include routine discussion of external validity. It is our hope that these evaluation and reporting standards help rebalance scientific inquiry, such that the current obsession with causal inference is complemented with an equal interest in generalized knowledge.

Scholars have long examined the relationship between natural resources and conflict at the country level. More recently, researchers have turned to subnational analyses, using either individual countries or subnational data for a small number of resources in sub-Saharan Africa. We introduce a new sub-national dataset of [Formula: see text] resources that adds many resource types, locations, and countries from Africa, the Middle East, Asia, Latin America, and Europe. To demonstrate the value of the new dataset, we examine how conflict incidence varies with the value of the collective set of resources in a given location using world prices. We then introduce new country-specific price data, which are more relevant for conflict dynamics. Since country-specific prices can be endogenous to conflict, we instrument country-specific prices using U.S. and world prices. We find that sub-national resource wealth is associated with higher levels of conflict using some specifications, though the results vary widely by data source and world region. Using an instrumental variables strategy lends the strongest support to this positive relationship, but only for African countries. Notably, across all of our models, we find that resources are negatively associated with conflict in Latin America, suggesting heterogeneity of effects worth future exploration.