This article examines party institutionalization in Hong Kong in order to understand the development of political parties in a political system undergoing democratization. Party institutionalization is defined as the extent to which political parties develop a systematic set of mechanisms and structures that enable them to compete effectively for political power. By examining partisanship, autonomy, and the stability of political parties in Hong Kong, the author concludes that party institutionalization is still weak, although there are signs of progress. Constitutional constraints, structural factors, lack of public support, and the problem of adaptation pose serious obstacles in the party institutionalization process. Political parties, as one of the essential conditions for democratic consolidation, have brought a new page of democratic politics to Hong Kong. However, in terms of institutionalization, political parties in Hong Kong are far from mature, thereby limiting their impact on the democratization process.