trans-2-Benzylidene-1-diphenylmethyleneindane undergoes a thermal distrotatory and a photochemical conrotatory ring closure followed by a suprafacial [1,5] hydrogen shift, to give cis- and trans-10,10a-dihydro-5,10-diphenyl-11H-benzo[b]fluorene, respectively. The 3-methyl derivative of the diene undergoes analogous rearrangement reactions but only one dihydrobenzofluorene is obtained in each of the thermal and photochemical reactions, indicating that steric effects determine which of the two possible disrotatory or conrotatory processes occur.