If we consider the large number of possible applications of poly(lactic acid) (PLA) in the biomedical field and in the biodegradable packaging applications, just to name two of the most important ones, the study of their crystallization will always be decisive to tailor their properties. Additionally, the production of a high impact PLA with improved thermal stability and processability is still under investigation. Crystallization is likely to play a vital role in the development of future PLA-based materials. The morphology and crystallization behaviour of PLA have been extensively studied by different analytical techniques, such as WAXS/SAXS, TEM, PLOM, AFM and DSC. The extensive review of the most recent literature results indicates some general features and they are presented in this chapter.