This paper reports on a novel approach to providing undergraduates with feedback on STEM writing assignments via an otherwise untapped educational resource: university alumni and employees who normally play no role in the institution's educational mission. In the Volunteer Expert Reader (VER) approach, students are paired with volunteers whose backgrounds make them suitable readers for specific writing assignments. Given the realities of labor in STEM undergraduate teaching contexts, VER may be particularly valuable there, facilitating student interactions with experienced STEM professionals who have the time and inclination to give them substantive feedback on their writing based on real-world experience. Results from this 3-year study suggest that (1) VER can be an effective means of increasing student engagement in STEM writing assignments and may also improve the quality of student writing and increase learning of course content; and (2) how well VER works for any STEM writing assignment is dependent on a number of factors including whether student participation is required, whether students write alone or as a team, how well readers' backgrounds fit the assignment, and reader engagement and availability to students. VER is also an effective faculty development tool: it offers faculty in STEM disciplines a compelling reason to collaborate with writing program administrators and necessitates the inclusion of best practices in writing assignment design, such as making explicit the rhetorical context and aims of the writing task and setting a reasonable pace for drafting/revision cycles.