It's a simple fact — the majority of today's engineers are men. However, more and more women are electing to study with, work alongside, and help lead their male counterparts in this complex, diversified, and ever-changing field. Sony's Andrea Wong, Yahoo's Marissa Mayer, and former U.S. EPA head Lisa Perez-Jackson are just a few examples of women who are striving and thriving in the STEM arena. This photo gallery takes a look at seven pioneering women who, against some pretty big odds, helped pave the way for other women considering a career in the field of engineering. Let's hear it for the ladies!