Strong gravitational lensing has become a cornerstone of modern astrophysics and cosmology. By probing the total (baryonic + dark) mass distribution, it provides unique insights into the assembly and evolution of galaxies and clusters. Acting as “cosmic telescopes”, gravitational lenses magnify distant sources, allowing us to peer deeper and farther into our Universe. In the next few years, Euclid and Rubin will provide imaging and time-domain datasets of unprecedented depth, quality, and scale, enabling the discovery of >10⁵ lenses and hundreds of transient events (lensed supernovae and quasars). Combined with photometric and spectroscopic surveys from other facilities and the next generation of telescopes (e.g. JWST and Roman), these data will revolutionise studies of galaxy, cluster and AGN evolution, of dark matter, and of key cosmological parameters, such as the Hubble Constant and the dark energy equation of state. 

The Focus Meeting 12, “Strong Gravitational Lensing in the Era of Euclid and Rubin”, at the XXXIII International Astronomical Union General Assembly, will be held on 18–19 August 2027 in Rome, Italy. The meeting aims to bring together observers and theorists to discuss the first scientific results from Euclid and Rubin, coordinate community standards, and define the priorities and challenges for the coming golden decade of strong lensing science.