Developing effective structure-activity/property/toxicity relationships (QSAR/QSPR/QSTR) is very helpfulin predicting biological activity, property, and toxicity of a given set of molecules. Regular change inthese properties with the structural alteration is the main reason to obtain QSAR/QSPR/QSTR models.The advancement in making different QSAR/QSPR/QSTR models to describe activity, property, andtoxicity of various groups of molecules is reviewed in this chapter. The successful implementation ofConceptual Density Functional Theory (CDFT)-based global as well as local reactivity descriptors inmodeling effective QSAR/QSPR/QSTR is highlighted.