The codivergence of mating traits and mate preferences may generate assortative mating pattern and limit gene flow between divergent lineages in the early stages of speciation. However, this assumed behavioral isolation is effective only when assortative mate preferences lead to assortative mating patterns. Elucidating the factors mediating how preference translate to choice is thus imperative to understanding the role of divergent mate preferences in speciation. In the extremely color polytypic strawberry poison frog (Oophaga pumilio), female mate preferences have codiverged with color in most allopatric populations tested. However, the degree to which these divergent preferences can effect reproductive isolation in the wild is unclear. We investigated color assortative mate choice in a contact zone where a red and a blue morph co-occur naturally. When assayed in the lab, females, regardless of their own coloration, show a universal preference toward males compared to blue or phenotypically intermediate males. However, observations in the wild found evidence of color assortative mating: mating success in homomorphic courting pairs is significantly higher compared to heteromorphic pairs. We further used microsatellite markers to reconstruct the pedigree relationships among captured adults, juveniles, and tadpoles in a mark-recapture plot. Intriguingly, results show assortative mating tendency in red females, but not in blue or intermediate females. The discrepancies found among mate preference, mate choice, and mating pattern between the divergent red and the blue morphs of O. pumilio highlight the complexity of how assortative mate preference drives the evolution of reproductive isolation.