2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/14278Methods for the determination of star formation rates (SFR) from integrated populations are reviewed. We discuss the assumptions and underlying uncertainties (e.g. IMF slope, M_up, metallicity, SF history etc.) used in the calibrations of UV, FIR, Halpha, and [OII] indicators. The ``universality'' of empirically calibrated indicators such as [OII] is examined. We also present preliminary results from a theoretical study with the aim to understand the systematics of forbidden line indicators and to provide new SFR indicators including optical to far-IR lines.12 pages, including 7 figures. Invited review, to appear in ``Building the Galaxies: from the Primordial Universe to the Present'', XIXth Moriond astrophysics meeting, F. Hammer et al. (eds.), Editions Frontieres (Gif-sur-Yvette); (minor changes to references)Astrophysicstext