Crystallization analysis fractionation (Crystaf) and temperature rising elution fractionation (Tref) are analytical techniques for determining the distribution of chain crystallizabilities of semicrystalline polymers. These techniques fractionate polymer chains on the basis of the differences in their chain microstructures that affect their crystallizabilities in dilute solutions. Both techniques can be used to estimate the chemical composition distribution of copolymers and the tacticity distribution of homopolymers. This information is crucial for understanding polymerization mechanisms and constructing structure-property relationships. This review covers the theoretical aspects of both techniques, describes their basic operation procedures and applications, and discusses the mathematical models proposed for Crystaf and Tref.