The assignment of the NMR spectra of natural abundance medium-sized solid-state organic molecules still represents a challenging problem. In this paper, we show that a complete assignment of all the carbon-13, nitrogen-15, and proton NMR lines of a natural abundance solid peptide can be performed by combining various one-bond and multiple-bond correlation techniques for rotating solids. The assignment of the MAS spectra is shown to be unambiguous and relatively straightforward.