Traditionally, rational-basis scrutiny is extremely deferential and rarely invalidates legislation under the Equal Protection Clause. However, a small number of Supreme Court cases, while purporting to apply rational-basis review, have held laws unconstitutional under a higher standard often termed “rational basis with bite.” This Note analyzes every rational-basis-with-bite case from the 1971 through 2014 Terms and nine factors that appear to recur throughout these cases. This Note argues that rational basis with bite is most strongly correlated with laws that classify on the basis of an immutable characteristic or burden a significant right. These two factors are particularly likely to be present in rational-basis-with-bite cases, which can be explained on both doctrinal and prudential grounds. This conclusion upends the conventional wisdom that animus is the critical factor in rational basis with bite and reveals that other routes to rational basis with bite exist. Finally, this Note observes that applying at least rational basis with bite to discrimination against gay, lesbian, bisexual, and transgender individuals is consistent with the pattern of cases implicating immutability and significant rights.