The core meaning of identity is to reveal something’s nature and to make it a part of one’s self concept. Since identity has long been seen as the source of human behavior, it has received a lot of attention in academia. In the 1970s, rooted from the curiosity of defining oneself, psychologists focused their research on self identity. In the 80s, social identity theory (Tajfel, 1982) and organizational identity theory (Ashforth, 1989) shifted research foci from self-focused to group-focused. This shifted paradigm focused on how individuals summarize group identity (organizational identity) and transform it into a part of self concept. Thirty years later, organizational identity has become a blooming topic and has established its place in organizational behavior research. The main purpose of this article is to provide a systematic review of what has been studied in identity over the last few decades. We first introduce the concept evolution of identity. Second, we summarize current research as four trends,then evaluate both the contributions and limitations of each trend. Last, we propose a roadmap for future research by addressing some current, cutting-edge issues. On the basis of this review, we try to advance our knowledge of identity and illustrate an agenda for theoretical developments and empirical explorations.