Utility-value interventions, in which students complete writing assignments about the personal usefulness of course material, show great promise for promoting interest and performance in introductory college science courses, as well as persistence in STEM fields. As researchers move toward scaling up this intervention, it's important to understand which features are key to its effectiveness. For example, prior studies have used different types of utility-value assignments (i.e., self-focused essays and other-focused letters) and different assignment structures (i.e., over time, researchers provided a variety of tasks or choices between tasks), without comparing them. It is not known whether these assignment features are incidental details or key aspects of the intervention that impact its effectiveness. In the current study, we systematically compared different utility-value assignments, as well as ways of combining them, in a randomized controlled trial in an introductory college biology course (N = 590). Specifically, we compared different versions of the intervention in terms of their relative effectiveness for promoting course performance and the motivational mechanisms through which they operated. The intervention was most effective when students had opportunities to write about utility for both the self and others. Grades were higher in conditions in which students were either assigned a variety of self-focused and other-focused assignments or given the choice between the two. Among students with low performance expectations, grades were higher when students were assigned a specific combination: a self-focused assignment followed by other-focused assignments. Results suggest that different versions of the intervention may work through different mechanisms.