AbstractDensity functional theory (DFT) calculations are reported for Eu@C74, where the considered C74 cage is either the IPR (isolated pentagon rule) species or two cages with a pentagon–pentagon junction. Their relative thermodynamic production yields are evaluated using the DFT calculated terms and it is shown that the IPR‐based Eu@C74 endohedral prevails at relevant temperatures in agreement with observation, however, isolation of a minor isomer should be possible.