FRET between luminescent nanoparticles is a compromise between outstanding photophysical properties and large sizes. In their Review Article (e202510801) Niko Hildebrandt, Chloé Grazon et al. discuss the influence of nanoparticle type, architecture, surface chemistry, and optical properties on FRET and the pros and cons of inter-nanoparticle FRET for bioanalytical applications.