Researchers and policy makers often use the metaphor of an ever-narrowing pipeline to describe the trajectory to a science, technology, engineering or mathematics (STEM) degree or career. This study interrogates the appropriateness of the STEM pipeline as the dominant frame for understanding and making policies related to STEM career trajectories. Our review of pertinent literature and independent analysis of data from the National Educational Longitudinal Study of 1988 finds that the trajectory implied by the pipeline metaphor fails to describe the experience for nearly half of those who go on to become scientists or engineers, masks meaningful differences in trajectories by subfield, and informs policies that do little to diversify or increase the size of the STEM workforce. We suggest a pathway metaphor to better illuminate the multiple trajectories toward STEM degrees and careers and present four composite trajectories as useful categorizations of the individual paths taken by STEM graduates and career entrants.