The ground level of the Cr3+ ion in a tetrahedral environment is analyzed. In particular, it is shown that the calculation based on an undistorted tetrahedral ligand field yields a Γ7 level in the ground state whereas the ground state in the presence of a dynamic Jahn–Teller effect (vibrational E mode) of strength given by EJT > 8a, where EJT is the Jahn–Teller energy and a is a second-order spin–orbit coupling parameter, is aΓ8. The expected nature of electron spin resonance spectra is discussed.