The goals and methods of a longitudinal study of language development of eight Korean-English bilingual children are reported. The children were ages 4-8 at the beginning of the study. The goals of the study were (1) to document and analyze the development of English in natural communicative contexts, (2) to study the pattern of language shift from Korean to English, (3) to examine the effects of age and sibling order on English development, (4) to study the relation between the subjects' interpersonal oral language ability in natural settings and their comprehension of school tasks, and (5) to provide information for improving language instruction. The study calls for monthly observations of the children for three years at school and at home. The methodological features of the study and the structural characteristics of some selected linguistic features of Korean and English are described. General language characteristics across subjects are detailed, including the amount of speech and the frequency of speech turns in each language and the length of utterance. The language samples of each subject are analyzed in terms of the various levels of linguistic structures. (RW)