The X-ray structure analysis of the aziridinyl peptide EtO-Azi-Gly-Gly-OBn indicates that the linear conformation adopted in the crystalline state is established by an intermolecular hydrogen bonding network. This is confirmed by force field computations. They show that the intermolecular interactions in the crystal are stronger than the intramolecular ones which for a single molecule would lead to a bent structure. As expected, the stabilization energies strongly decrease with increasing polarity of the environment. For medium polar environments, the intermolecular interactions are still stronger than the intramolecular ones which is in nice agreement with results from H-1 NMR dilution studies in CDCl3. For very polar environments, the intramolecular interactions become stronger than the intermolecular ones, however, if the solvent is able to form stable hydrogen bonds, e.g., DMSO, the intramolecular hydrogen bonds are replaced by hydrogen bonds to the solvent molecules. Raman spectra of the crystalline compound prove that the aziridine NH as well as the peptide bonds are involved in hydrogen bonding.