Specialized training in English diction for singers became increasingly prevalent in the twentieth century. Along with this growth, a small but significant literature on the subject developed. There are divergent practices recommended for American singers, displayed by nine authors in ten books published between 1900 and 1971. A comparative study yields pedagogies of vowel and consonant production. Issues of sounds in context, including proper linkage and stress, adjustments from speech to song, and practices dictated by musical style, are paramount. The literature demonstrates an increased use of International Phonetic Alphabet symbols as a pedagogical tool. The areas of kinesiology and acoustical research are suggested for further study.