Why is it preferable to say "salt and pepper" over "pepper and salt?" Based on an analysis of 692 binomial tokens from online corpora, we show that a number of semantic, metrical, and frequency constraints contribute significantly to ordering preferences, overshadowing the phonological factors that have traditionally been considered important. The ordering of binomials exhibits a considerable amount of variation. For example, although "principal and interest" is the more frequent order, "interest and principal" also occurs. We consider three frameworks for analysis of this variation: traditional optimality theory, stochastic optimality theory, and logistic regression. Our best models—using logistic regression—predict 79.2% of the binomial tokens and 76.7% of types, and the remainder are predicted as less frequent—but not ungrammatical—variants. [ABSTRACT FROM AUTHOR]