Little is known about the genetic mating system of the Kemp’s ridley sea turtle, Lepidochelys kempii. Jensen et al. (2006) found a positive relationship between the incidence of multiple paternity (MP) and the estimated population size of rookeries. In the high density Kemp’s ridley Rancho Nuevo rookery, Kichler et al. (1999) estimated 81% of nests were multiply sired (Wang 2004). If MP is positively related to nesting female density, then MP in Kemp’s ridley should be lower on a low-density nesting beach on South Padre Island, Texas (SPI) than in a Mexico’s much larger nesting population. We genotyped 154 hatchling tissue samples from nests on SPI at 14 microsatellite loci. Results using full sibship reconstruction as implemented in COLONY indicated that 52% of nests with two or more samples (11 of 21) exhibited MP. This suggests that this species does not follow the female density trend proposed by Jensen et al. (2006) and maintains high levels of MP and genetic variation across its nesting range.