The change in information technology demands drastic change in digital library service. This study defines what a social semantic digital library should consist of and proposes a new architecture that incorporates core functions needed in designing a SSDL. The SSDL supports semantic information processing based on metadata and ontology and is an innovation system that allows SSDL users to participate in generating new knowledge by interacting with existing metadata and ontology structures. This study designed a SSDL model that consists of five horizontal and two vertical structures.