 Many Essentialists have been skeptical of the reliability of uncleaned, unanalyzed corpus data as evidence to support linguistic theorizing, because it is assumed to be replete with strings that any native speaker would judge unacceptable. And many Emergentists and Externalists, as well as some Essentialists, have charged that informally gathered acceptability judgments can be highly unreliable too. Both worries are apposite; but the former does not hold for adequately cleaned and analyzed corpora, and the latter does not hold for judgment data that has been gathered using appropriately controlled methods. In certain contested cases of acceptability, it will of course be important to use both corpus and controlled elicitation methods to cross-compare.