The living polymerization of the metallocenyl-substituted diethynyltolan, 4-(ferrocenylethynyl)-4’-ethynyltolan (I), by the well-defined Schrock metathesis catalyst Mo(N-2,6-i-Pr2C6H3)(CHCMe2-Ph)(OCMe(CF3)(2))(2) (II) is described. The polymerization starts virtually solely via beta-addition of the monomer to the metal-carbon double bond and yields conjugated, surprisingly soluble, main chain polyenes containing mesogenic, rigid side chains. Despite the beta-addition, the polymerization proceeds in a controlled, living manner, resulting in the the formation of low polydispersity polymers. The resulting polymers exhibit a remarkable stability against air and thermal treatment.