Though their unique optical properties are proving advantageous for numerous applications, an ongoing challenge facing upconverting nanoparticles (UCNPs) remains achieving satisfactory upconverted signal and quantum yield while illuminating at low fluences. Here, I will describe the pros and cons of various strategies used to improve UCNP signals and efficiencies, which are pushing UCNP brightness to unprecedented levels. Of particular note here are advances in dye-sensitized UCNPs,1 high-lanthanide-content compositions,2,3 exploitation of stimulated emission,4,5 and, most recently, the realization of photon avalanching lanthanide-based nanoparticles.6 The impact of these concepts is now being widely felt in fields spanning deep-tissue imaging, optogenetics, remote sensing, anti-counterfeiting, and solar light harvesting