 Traditionally, philosophers of probability have recognized five leading interpretations of probability—classical, logical, subjectivist, frequentist, and propensity. But recently, so-called best-system interpretations of chance have become increasingly popular and important. While they bear some similarities to frequentist accounts, they avoid some of frequentism’s major failings; and while they are sometimes assimilated to propensity accounts, they are really quite distinct. So they deserve separate treatment.