The Korean IT industry has shown distinct patterns in learning mechanisms and organisational configuration throughout its entry into advanced information technology. Innovation systems in the area of information technology have also evolved along with technological capability, thereby changing the focus of technological strategies and the role of public institutions. It is found that distinctive patterns of learning and diffusion mechanisms in the case of DRAMs, TDX, and CDMA systems represent successful catch-up situations in Korea as presented in this paper. This paper characterises the stylised facts of the Korean innovation system in the IT sector and traces how technology and institutions coevolved throughout the development process. The transition from technology-using to technology-generating is not an automatic process. Cumulative learning in both technology and organisation is a critical factor to upgrade technological capabilities. The main policy implication of the paper is that it is important to design the cot-responding organisational and institutional arrangement in accordance with the changing need of technological upgrading.