In 2015, mathematics leaders and instructors from the Society for Industrial and Applied Mathematics (SIAM) and the Consortium for Mathematics and Its Applications (COMAP), with input from NCTM, came together to write the "Guidelines for Assessment and Instruction in Mathematical Modeling Education" (GAIMME) report as a resource for teachers who want to incorporate the practice of mathematical modeling in their classrooms. The GAIMME report, which can be downloaded for free (http://www.siam.org/reports/gaimme.php), provides insight into the modeling process, what mathematical modeling looks like across the grades, the role of the teacher, and how to assess students' modeling processes. The GAIMME report provides a sense of what mathematical modeling is and is not, as well as practical advice on how to teach modeling through the grade levels. It is consistent with but not limited to how the Common Core (CCSSI 2010) includes modeling as one of the Standards for Mathematical Practice that are meant to span kindergarten through grade 12. The GAIMME authors demonstrate the importance of mathematical modeling and how and why it should be an essential part of every student's mathematics experience throughout their education. This article, written by members of a joint committee between NCTM and SIAM, serves as an introduction to the GAIMME report and offers information on how to incorporate modeling into the high school mathematics classroom.