Atactic poly(vinyl alcohol) (PVA), which has some branches or acetyl groups, was crystallized by shearing force under turbulent flow from its aqueous solution in order to clarify the effects of branches or acetyl groups on the shearing stress-induced crystallization. The crystallization became more difficult with an increase in their number. In partially acetylated PVA, the acetyl groups of randomly acetylated PVA markedly influenced the shearing stress-induced crystallization in comparison with that of nonrandomly acetylated PVA. In addition, this paper describes the shearing: stress-induced crystallization under laminar flow of syndiotactic-rich PVA partially acetalized with glyoxylic acid.