As postdoctoral appointments have become more common and prolonged  (Stephan and Ma, 2005) especially in the life sciences, scientists and those who employ them seek to better understand who  becomes a postdoctoral scholar (postdoc) and why. There is concern that postdoctoral appointments have become a holding pattern and a source of cheap labor  (Mishagina, 2009, Puljak and Sharif, 2009). On the other hand, other studies have found that the most talented new PhDs also become postdocs  (Zumeta, 1985, Vogel, 1999). This paper reviews the literature and advances a series of propositions to guide future research on new entrants to the postdoctoral workforce.