We review the rapid progress during the last years in the study of secondary emission in quantum wells. On the experimental side, this progress was characterized by ever increasing temporal, spectral, and spatial resolution. On the theoretical side, the most appropriate description of the resonant low-excitation regime is the paradigm of disorder-localized exciton center-of-mass wavefunctions as developed by Roland Zimmermann and collaborators. In our contribution to this Festschrift, we focus on the recent developments in the study of secondary emission and on the major contribution by Roland Zimmermann to the understanding of such phenomena.