2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/6474Evidence for the existence of Mira Period-Luminosity relations is reviewed including recent work on Miras with thick circumstellar shells. The calibration of the relation at K is discussed in detail. The nature of variables deviating from the PL relation and possible metallicity effects are also discussed.8 pages, to appear in "Variable Stars in the Local Group" (IAU Colloqium 193) ASP Conf. SerAstrophysicstext