This paper examines the history of four Chinese vernaculars which have developed written forms, and argues that five of the patterns Hanan identifies in the early development of Bai Hua can also be found in the early development of written Wu, Cantonese, and Minnan. In each of the cases studied, there is a clear pattern of early use of the vernacular being sanctioned by the following factors: (1) a tie to oral literature; (2) use in texts written for less literate audiences; (3) a tie to low prestige domains; (4) association with groups that have little fealty to the dominant culture; and (5) use in new genres, where conventions are not already set. The strength of these patterns, found in cases that differ in both social and historical setting, suggests that they are rooted in inherent attributes of L varieties in diglossic situations, and that similar patterns may well be found in other cases where L varieties begin developing written forms.