Improving the crystallization behavior of poly(L-lactide) (PLLA) is a major research focus that could enlarge the potential for applications. Addition of nanofiller, which acts as a nucleating agent, has been shown to improve the crystallization behavior of PLLA. The content of the nanofiller exhibits a great role in determining the crystallization behavior. This is because both the density of nucleation sites and the growth rate of crystallites of PLLA are influenced by the content of the nanofiller. On page 183, Yong Wang and colleagues comparatively study the different effects of carbon nanotubes and montmorillonite on crystallization behaviors and mechanical and thermal properties of PLLA. They show that the two nanofillers exhibit different network structures. Consequently, different crystallization behaviors of PLLA are observed.