In recent decades, there have been many campaigns to attract students to STEM study programs and jobs. However, there is little research on whether the target audiences are familiar with the STEM acronym, which specific STEM subject areas they associate with it, and the impact of these associations. We investigated students’ familiarity with the STEM acronym and whether their associations of the STEM acronym with different STEM subject areas—mediated by their value beliefs—affected their academic elective intentions for STEM study programs and activities and their STEM choices of curriculum profiles at school. In a sample of eighth-grade students (n = 1163; 611 girls; 13.7 years), 72% reported familiarity with the STEM acronym. Students associated mathematics most strongly with the STEM acronym, followed by physics, computer science, chemistry, biology, and engineering. The subject areas students associate with the STEM acronym affected their academic elective intentions for STEM and their STEM choices at school. These relations were mediated by students’ value beliefs and differed for the subject areas associated with the STEM acronym and by gender. The consequences of our findings for tailoring STEM campaigns to ensure their effectiveness and a more diverse and inclusive STEM community are discussed.