Soto worked at the
University of Southern Colorado from 1989 to 1992 as director of the Mathematics Learning Center. In 1995, she became an assistant professor of mathematics at the university, earning tenure there as an associate professor in 2001; the university became known as Colorado State University–Pueblo in 2003. In 2005 she moved to the University of Northern Colorado, taking a step down to become an assistant professor again. She was promoted to associate professor in 2008 and to full professor in 2014, before moving to Colorado State University as a professor of mathematics. At the University of Northern Colorado, Soto founded and directed a summer program for high school girls, Las Chicas de Matemáticas: UNC Math Camp for Young Women, from 2008 to 2014, and returned to rural Nebraska to participate in a teacher education program there, Math in the Middle. She is a fellow of
Project NExT, and has been governor of the Rocky Mountain Section of the
Mathematical Association of America. She is also a principal investigator of the
Embodied Mathematical Imagination & Cognition project. She has a long association with the MAA and has been increasingly involved with its governance. In May 2018, she took over from Gerald Venama as its Associate Secretary. In October 2021, she was elected as President-Elect of MAA and is serving a two year term, starting February 1, 2022. ==Recognition==