Many species of frog exhibit striking color and pattern polymorphisms, but the genetic bases of these traits are not known for most species. The coqui frog, Eleutherodactylus coqui, a species endemic to the island of Puerto Rico, exhibits a wide variety of color and pattern polymorphisms including 4 discrete stripe patterns on its dorsal surface and an unstriped morph. We conducted breeding experiments to determine the mode of inheritance for these 5 dorsal color patterns in E. coqui. We analyzed results from 14 different cross types, which included 1519 offspring from 71 clutches. We found that color patterns segregate at ratios consistent with a single autosomal locus, 5-allele model, in which all alleles coding for stripes are codominant and the allele coding for the unstriped morph is recessive. We propose that this locus be named "stripes" with alleles B (interocular bar), L (dorsolateral stripes), N (narrow middorsal stripe), W (wide middorsal stripe), and u (unstriped). The results of this experiment suggest the genetic basis of stripe patterns in this well-studied species and provide a model for studying the evolution and maintenance of this phenotypic polymorphism.