Isoxazoles, isoxazolines and isoxazolidines are a class of heterocyclic compounds having a remarkable number of applications and are very versatile building blocks in organic synthesis. The developments concerning the synthesis of the above monocyclic systems reported in the literature from 2007 to 2019 are reviewed. Some data related to theoretical methods, experimental structural methods, and thermodynamic aspects for this class of heterocycles are also reported.