The relationship between the size of the broad-line region (BLR) radius and the luminosity in AGN is the cornerstone for scaling relations that use single epoch spectra of high-redshift quasars to estimate their masses. We have undertaken various projects to improve the accuracy to which the radius-luminosity relationship is known. We account for host- galaxy starlight contributions to luminosity measurements using high-resolution HST images of the central regions of reverberation-mapped AGN. Initial results show that removing the starlight component results in a significant correction to the luminosity of each AGN, not only for the lower-luminosity sources but also for the higher-luminosity sources such as the PG quasars. We have also implemented new ground-based monitoring programs to replace earlier, inadequate BLR radius measurements for several reverberation-mapped AGN.