From its modest beginnings in the 1950s, nuclear magnetic resonance (NMR) spectroscopy has become the premier analytical tool for the determination of structure of organic natural products. Structural elucidation efforts were originally limited to proton NMR and typically required both relatively large quantities of material and considerable time. However, modern NMR spectrometers, with an array of one- and two-dimensional experiments, permit the structures of complex organic molecules to be determined, often in a day, using less than 1 mg of sample. This chapter will prepare natural product chemists to employ modern NMR techniques effectively in the determination of molecular structures. It focuses on the rapid determination of whether an isolated compound is known or new, the information content of various two-dimensional and selective one-dimensional NMR experiments, the use of these experiments in combination and avoiding or overcoming common pitfalls in determining molecular structures, the selection of optimum acquisition parameters and data processing methods and parameters, and the use of computer-assisted structure elucidation.