Horizontal segregation in the higher education framework is a problem that goes up in the work environment. Women are assuming traditional gender roles due to phenomena such as the threat of stereotyping, which prevents them from opting for higher studies in science, technology, engineering and mathematics (STEM). This research work arises within the project W-STEM, “Building the Future of Latin America: Involving Women in STEM”. The research aims to investigate women’s academic and professional development in science, technology, engineering and mathematics (STEM) through their personal experience in making career-related decisions. The research was developed by applying a qualitative method. During the year 2020, video semi-structured interviews were conducted with twenty-one women professionals in the STEM field. Of the twenty-one participants, six are linked to science, eight to technology, fifteen to engineering and one to mathematics. Due to their research lines, some of them are located in more than one STEM area, for example, in technology and engineering. These women were interviewed about their choice of studies and training, their jobs, professional achievements, family and social environment and their perspective on the gender gap in STEM. They all agree on horizontal segregation and consider it necessary to motivate girls and young women to study what they like. Furthermore, they all show passion for their work.