Learning about letters is an important foundation for literacy development. Should children be taught to label letters by conventional names, such as /bi/ for "b", or by sounds, such as /b[inverted e]/? We queried parents and teachers, finding that those in the United States stress letter names with young children, whereas those in England begin with sounds. Looking at 5- to 7-year-olds in the two countries, we found that U.S. children were better at providing the names of letters than were English children. English children outperformed U.S. children on letter-sound tasks, and differences between children in the two countries declined with age. We further found that children use the first-learned set of labels to inform the learning of the second set. As a result, English and U.S. children made different types of errors in letter-name and letter-sound tasks. The children's invented spellings also differed in ways reflecting the labels they used for letters. (Contains 9 tables.)