The sections in this article are 1 Introduction 2 Why Higher Dimensions? 3 Classification of Multidimensional NMR Experiments 4 The Design of Multidimensional Homonuclear Experiments 5 Selective and Nonselective Homonuclear 3D NMR 6 Principles of Homonuclear 3D Spectroscopy 7 Practical Aspects 8 Applications 9 Prospects for 3D NMR Spectroscopy 10 Biographical Sketches Related Articles