This study compared two expectancy-value-theory-based interventions designed to promote college students' motivation and performance in introductory college physics. The utility value intervention was adapted from prior research and focused on helping students relate course material to their lives in order to perceive the material as more useful. The cost reduction intervention was novel and aimed to help students perceive the challenges of their physics course as less psychologically costly to them. Students (N = 148) were randomly assigned to the utility value intervention, cost reduction intervention, or a control condition. Participants completed intervention or control activities online at 2 points during the semester. Their motivational beliefs and values were measured twice, once immediately after the intervention or control activities ended and again at the end of the semester. Both interventions improved students' grades and exam scores relative to the control group (ds from 0.24-0.30), with stronger effects for students with lower initial course exam scores (ds from 0.72-0.90). Unexpectedly, both interventions' effects were explained in part by initially lower performing students reporting higher competence-related beliefs and lower cost immediately after they received either intervention compared with lower performing students in the control condition. Results suggest that cost reduction and utility value interventions are both useful tools for improving students' science, technology, engineering, and mathematics course performance.