This study investigates the relationship between maternal skin tone and low birth weight among Puerto Ricans, a group with a complex ancestry and skin tones that range from very light to very dark. Using data from a representative sample of Puerto Rican mothers, we assess whether skin tone has different implications for low birth weight in three geographic areas (Puerto Rico; New York City; other eastern states). The analysis shows that skin tone is unrelated to low birth weight in Puerto Rico and New York City. However, in the other eastern states in our sample, mothers with dark skin have a high risk of bearing a low birth-weight infant, relative to mothers with light skin. We interpret our findings in light of differences in the social meaning of phenotypic differences across locales.