The 2018 NSSME+ was based on a national probability sample of schools and computer science, mathematics, and science teachers in grades K-12 in the 50 states and the District of Columbia. The sample was designed to yield national estimates of course offerings and enrollment, teacher background preparation, textbook usage, instructional techniques, and availability and use of facilities and equipment. This report describes novice and veteran mathematics teachers in the United States, with particular emphasis on the similarities and differences between these two groups. Although the focus of the 2018 NSSME+ was not on novice teachers, the dataset contains 863 teachers who reported being in their first five years of teaching mathematics, including 235 elementary grades teachers (defined as teaching any grade K-5 or teaching a self-contained 6th grade class), 285 middle grades teachers (teaching 6th grade non-self-contained or grades 7-8), and 343 high school teachers (grades 9-12). Because of the sample design and the use of design weights in analysis, results of the 2018 NSSME+ are nationally representative. Consequently, the results presented in this report should be interpreted as indicative of all novice and veteran mathematics teachers, not just those who participated in the study. The standard errors for the estimates presented in this report are included in parentheses in the tables. Details on the survey sample design, data collection and analysis procedures, and creation of composite variables are included in the "Report of the 2018 NSSME+" (ED598121). This report is divided into five main topic areas. Following the introduction in chapter 1, chapter 2 provides data about the school contexts in which teachers worked. Chapter 3 highlights characteristics of teachers themselves, including sex, race/ethnicity, age, and experience. The fourth chapter describes preparation for teaching mathematics, including college degrees, college-level mathematics coursework, and professional development experiences. Chapter 5 provides data about teachers' beliefs about teaching and learning and perceptions of preparedness to teach mathematics. The sixth chapter describes the nature of instruction in teachers' classrooms, including objectives for instruction, instructional strategies used, and availability of resources. The report concludes with a summary.