The two peptides, rich in Cα‐tetrasubstituted amino acids, Ac‐Aib‐L‐(αMe)Val‐Aib2‐L‐His‐NH2 (1) and Ac‐Aib‐L‐(αMe)Val‐Aib2‐O‐tBu (2 a) are prevalently helical. They present the unique property of changing their conformation from the α‐ to the 310‐helix as a function of the polarity of the solvent: α in more polar solvents, 310 in less polar ones. Conclusive evidence of this reversible change of conformation is reported on the basis of the circular dichroism (CD) spectra and a detailed two‐dimensional NMR analysis in two solvents (trifluoroethanol and methanol) refined with molecular dynamics calculations. The X‐ray diffractometric analysis of the crystals of both peptides reveals that they assume a prevalent 310‐helix conformation in the solid state. This conformation is practically superimposable on that obtained from the NMR analysis of 1 in methanol. The NMR results further validate the reported CD signature of the 310‐helix and the use of the CD technique for its assessment. Peptides that behave like a solvent‐sensitive molecular spring: Two short peptides elongate, adopting a 310‐helix conformation, in solvents of low polarity, while they shrink, adopting an α‐helix conformation, in highly polar solvents (see illustration).