The alkyne to 1,3-diene isomerization reaction is a process in which a nucleophilic phosphine catalyst promotes the rearrangement of an electron-withdrawing group activated alkyne to the corresponding conjugated diene. The origin, mechanism, development, and application of this organocatalytic and stereoselective reaction in the synthesis of complex organic molecules are reviewed. 1 Introduction 2 The Reaction 2.1 Background 2.2 Mechanism 2.3 Development 2.4 Synthetic Applications 3 Conclusions