Background/Context: Policy makers, school district officials, teachers and parents have embraced science, technology, engineering, and mathematics (STEM) subjects as a way to promote a stronger pipeline to college and career STEM. In so doing, these varied groups seek to raise job prospects for next-generation workers, increase opportunities for low-income and minority students, and enhance U.S. competitiveness in a global economy. Purpose/Objective/Research Question/Focus of Study: In this article we explore the ways in which the work of counseling departments in two different school environments shape students' STEM participation in high school, with important potential consequences for college and career STEM. High school counselors operate at a critical access point to high-level science and math coursework in high school and STEM postsecondary majors and programs after high school. A fuller understanding of the role that school counselors play in improving math and science outcomes and strengthening pathways to STEM is increasingly important, particularly given the push for STEM careers in new global economic context. Research Design: In this article we delve deeply into the day-to-day workings of the high school counseling office in two schools that serve markedly different populations of students. Utilizing data gathered through full ethnographic investigation over a 1-year period, we focus on the ways in which the work of counselors collectively constrain and/or enhance short and long-term STEM-linked outcomes for varying populations. We address two interrelated research questions: (1) In what ways and to what extent does the work of counseling departments in two different school environments shape students' STEM participation in high school? (2) In what ways and to what extent does the work of the counseling departments differ in schools that serve markedly different populations of students in terms of race/ethnicity and socioeconomic status? Conclusions/Recommendations: Our data reveal stark differences between students' high school STEM participation at the two schools. Evidence also points to differences in the work and role of school counselors in aiding students to access STEM in college and career. However, in spite of the fact that one school offers a far more robust pipeline to STEM than does the other, in neither case do the schools take concrete steps to maximize access to STEM in college or career for their top math and science students who express strong inclination in this direction. Although it is arguably the case that a number of factors contribute to STEM college and career outcomes, data highlight the differential yet simultaneously central role of high school counselors in the pipeline to STEM.