O'Reilly-Regueiro is originally from
Mexico City. She was a mathematics student at UNAM, graduating in 1995. For the next two years she continued to work at UNAM as an assistant in the mathematics department of the Faculty of Chemistry, while studying
harpsichord at UNAM's , working there with musician Luisa Durón. Next, with a scholarship from the UNAM Dirección General de Asuntos del Personal Académico (DGAPA), she traveled to England for graduate study at
Imperial College London, at that time part of the
University of London system. She completed her PhD in 2003. Her dissertation,
Flag-Transitive Symmetric Designs, was supervised by
Martin Liebeck. On completing her doctorate, she returned to UNAM as a researcher for the Institute of Mathematics. ==Recognition==