We present the first coupled cluster singles and doubles calculations of the scalar rotatory strength and the rotatory strength tensor, which determine the intensity of isotropic and oriented electronic circular dichroism spectra, respectively, for the ethylene chromophore of (-)-trans-cyclo-octene. Results for the oscillator strength of the ordinary electronic absorption spectra are also reported. The results are presented in pictorial form for seven different basis sets and two formally equivalent formulations of the intensity quantities. The theoretical results are compared with the experimental absorption and isotropic circular dichroism spectra of (+)-trans-cyclo-octene.