The purposes of this study are : (1) To examine young children`s written language development in terms of their characteristic behaviors related to written language, (2) to examine young children`s oral and written language awareness development. For these purposes, two groups of 16 children each ranging ages of 2 and 3, and three groups of 20 children each ranging ages of 4, 5, and 6 were selected from homes, play schools, nursery schools, and kindergartens. Children were interviewed individually in a quiet place at their own homes, play schools, nursery schools, and kindergartens. The interviews include : examining children`s understanding of the proper orientation of the books and children`s reading-writing abilities, discussing the content of the books, writing what children say to deliver the story content to a person not present, letting children write the stories and read their own hand written stories, letting children do block construction, talking with children about block construction, writing what children say to report their block construction and read hand-written stories about block construction. Children`s responses during the interview sessions were recorded and transcribed for later analyses. The results were as follows. 1. Before young children reached the stage of conventional reading, several pre-conventional reading behaviors appeared : Saying "No. " or "I can`t read. " since they have no storymaking abilities, making up stories, paraphrasing, reciting parts of the texts of stories, saying "I can`t read." knowing that it is the words people read but they do not know how to read. 2. Before young children reached the stage of conventional writing, several pre-conventional writing behaviors appeared : vertical scribbling, horizontal scribbling, making some letter-like figures, making figures similar to real letters, making actual letters with some errors in orientation, writing words with invented spelling, writing correct words, writing setence with partial errors in spelling. 3. Many children of age 2 through 6 often used oral language indiscriminately in both oral and written contexts. However, some children, less than those mentioned above were aware of and used written language in both contexts. There were a few children who were able to distinguish between oral and written language and use them appropriately to the situations. Especially, decontextualization and understanding the function of dictation seemed to be difficult for the children of these ages. 4. The results also indicate that age is not the important determinant of written language development and support Sulzby`s assertion that literacy develops in the child in a sociocultural context.