2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10113In this review I will describe progress that has been made in determining masses of galaxy clusters using `weak lensing' and how this technique my be applied in the future to determine the dark matter distribution both on supercluster scales and on the scale of galaxy haloes.plain latex; 15 pages; 6 postscript figuresAstrophysicstext