This First Look presents findings from the base-year survey of the newly launched High School Longitudinal Study of 2009 (HSLS:09), the first round of a study that will follow a ninth-grade cohort through high school and into their postsecondary years. HSLS:09 is the fifth in a series of National Center for Education Statistics (NCES) high school longitudinal studies that began in 1972 and have been continued with each new decade. The purpose of this report is to introduce new data, marking the release of the HSLS:09 base-year dataset, through the presentation of select descriptive tables. The findings presented here represent only a small sample of the relationships between data elements in a study that gathered extensive information from school administrators, counselors, teachers, and parents, in addition to students who were both surveyed and given a mathematics assessment focused on algebraic reasoning. This report provides a first look at selected findings from the base year of the High School Longitudinal Study of 2009 (HSLS:09). The HSLS:09 project focuses on understanding students' trajectories from the beginning of high school into higher education and the workforce. The core research questions for the study explore secondary to postsecondary transition plans and the evolution of those plans; the paths into and out of science, technology, engineering, and mathematics (STEM) fields of study and careers; and the educational and social experiences that are related to these shifts in plans or paths. Appended are: (1) Technical Notes and Methodology; and (2) Standard Error Tables. (Contains 20 tables and 4 footnotes.)