Gene activity is the prime mover in the living cell, driving a cell’s function at any given time. In my lab, we strive to obtain a quantitative, experimentally-based description of gene expression and regulation at the level of individual cells, individual transcription events and absolute numbers of molecules. This “mesoscopic” description provides a bridge between two existing levels of description: the molecular (microscopic) level, at which a wealth of information is available through classical biochemistry and biophysics in vitro; and the “macroscopic” level of gene-network topologies, obtained mostly through classical genetics, which lacks quantitative details of the underlying interactions. Our findings so far suggest that the kinetics of gene activity, and how it is modulated to vary expression level, display surprising universality across genes and organisms.