In plants, photoactivation of the light receptor phytochromes (phy) leads to phy binding to, and inducing phosphorylation and degradation of, a subset of basic helix-loop-helix transcription factors, called PIFs (for phy-interacting factors), thereby exciting their target transcriptional network. We have been examining the mechanisms underlying the signaling transactions at both the phy-PIF and PIF-genome interfaces. We have shown that the coordinated PIF and phy degradation results concomitantly in both transcriptional regulation of target genes and immediate feedback attenuation of signaling intensity by reducing photoreceptor abundance. We have identified PIF-regulated genes and a diverse network of these rapidly light-responsive genes that are direct targets of PIF quartet-regulated transcription. Moreover, the evidence unveils an intriguing dual-layered mechanism of regulation, whereby both the level of promoter binding-site occupancy, and in situ modulation of bound-transcription factor intrinsic activity, combine to generate a complex matrix of shared, but quantitatively differential gene expression patterns. Efforts to decipher the mechanism(s) underlying this phenomenon will be discussed.