The study of learners’ development of Korean language ability is a core area of Korean language education research. The aim of this study is to propose the contents and methods for a comprehensive and systematic longitudinal research design based on previous studies dealing with the development of Korean language ability of learners. Some points to consider when selecting the contents of the study for the development of Korean language ability of learners are as follows. First, the scope of research needs to be encompass not only the learner but also the learning context, including teachers, parents, school, and the community. Second, the rapid change point of language development needs to be explicated. Third, based on the balanced data collection in each area, learners’ oral data should be complemented. Fourth, indicators related to early literacy must be developed and strengthened. Fifth, changes in the media environment must be considered so that the contents reflect the new ways of communication, expressions, and understanding of learners. Therefore, a multiple point prospective panel design and various survey methods, such as interviewing, observation, and recoding need to be used when designing a research method for the development of Korean language ability of a learner.