Most second language writing studies have approached the L2 Writing phenomenon through the cognitive theoretical lens that situates writing as a mental activity that resembles psychological and mathematical problem-solving (Cumming, 2016, p. 69). "While research on second language writing has expanded exponentially in recent years, it has for the most part situated writing as a cognitive activity focused primarily on the learner" (Vollmer, 2002, p.1). It is important to note that unlike L2 Reading research which has a rich and long history, L2 Writing research is fairly young and has been around only since the 1960s. In addition, L2 Writing and writing in general is a complex and multifaceted phenomenon, and that is probably one the main reasons why to date there is no comprehensive L2 Writing theory. This paper discusses how three major L2 writing theories (the Contrastive Rhetoric Model, the Cognitive Model and the Sociocultural Model) approach L2 writing.