Studies of education and careers in science, technology, engineering, and math commonly use a pipeline metaphor to conceptualize forward movement and persistence. However, the “STEM pipeline” carries implicit assumptions regarding length, contents, and perceived purpose. Using the National Survey of College Graduates, we empirically measure each of these dimensions. First, we show that a majority of STEM workers report skills training throughout their careers, suggesting no clear demarcation between education and work. Second, we show that using on-the-job expertise requirements paints (...) a very different portrait of the STEM workforce—and persistence in it. Third, we show that STEM-educated workers are well-prepared for but dissatisfied with non-STEM jobs, complicating our understanding of leaving. Collectively, these results recommend expanded conceptions of STEM education and careers and contribute to studies of science and engineering workforce transitions and diversity. (shrink)