Photopolymerization is a rapidly evolving research field, supported by the growing demand for greener polymerization processes and the development of 3D printers used now for daily applications. With aim at developing dyes adapted for LEDs used in 3D printers, benzylidene cyclopentanones have been regarded as interesting structures due to their facile synthesis, low cost, high thermal and photochemical stability. Especially, benzylidene cyclopentanones proved to be better candidates than their benzylidene ketones analogue due to the rigidity provided by the central five-membered ring. As a result of this rigidification, higher monomer conversions could be obtained. Noticeably, benzylidene cyclopentanones could initiate one and two-photon polymerizations processes, what is relatively unusual for dyes to exhibit this dual photoinitiating ability. In this review, recent advances concerning benzylidene cyclopentanones are detailed. Compared to their acyclic analogues, a severe improvement of the photoinitiating ability has been demonstrated for benzylidene cyclopentanones, so that comparisons between these two families of photoinitiators is provided.