Molecular qubits that respond to light Spins in solid-state systems such as quantum dots and defect centers in diamond can easily be controlled by light for use in quantum information processing. More challenging is tuning their properties and making large arrays, something that can be done more easily with spins in molecules. Bayliss et al. combined the advantages of the two approaches by designing and characterizing three related molecular species that are optically addressable. The molecules consist of a central chromium ion surrounded by organic ligands, and their spin and optical properties can be tailored by simply changing the positions of methyl groups on the ligands. Science , this issue p. 1309