Abstract
It is widely believed that hadronisation leads to 1/Qcorrections to e+e− event shapes. We show that there are further corrections, proportional to (ln Q)A/Q with A = 4CA/β0 ≃ 1.6, associated with hadron masses and whose relative normalisations can be calculated from one observable to another. At today's energies these extra corrections can be of the same order of magnitude as `traditional' 1/Q corrections. They fall into two classes: universal and non-universal. The latter can be eliminated by suitable redefinitions of the observables.