The paper surveys overlap between corpus linguistics and variationist sociolinguistics. Corpus linguistics is customarily defined as a methodology that bases claims about language on usage patterns in collections of naturalistic, authentic speech or text. Because this is what is typically done in variationist sociolinguistics work, I argue that variationist sociolinguists are by definition corpus linguists, though of course the reverse is not true: the variationist method entails more than merely analyzing usage data, and not all corpus analysts are interested in variation. But that being said, a considerable and arguably increasing number of corpus linguists not formally trained in variationist sociolinguistics are explicitly concerned with variation and engage in what I call corpus-based variationist linguistics (CVL). I first discuss what unites or divides work in CVL and in variationist sociolinguistics. In a plea to cross subdisciplinary boundaries, I subsequently identify three research areas where variationist sociolinguists may draw inspiration from work in CVL: conducting multi-variable research, paying more attention to probabilistic grammars, and taking more seriously the register-sensitivity of variation patterns.