This paper reports findings from two studies of student writing performance carried out in undergraduate political science courses to test whether low-cost interventions could lead to improvements in writing outcomes. Students enrolled in an introductory comparative politics course (N = 180) and a sophomore-level survey course (N = 101) were randomly assigned to receive short instruction sessions in specific writing skills led by a faculty member or senior graduate student. In the first experiment, half the class received explicit instruction on writing (focusing on two specific skills from a comprehensive rubric that we subsequently coded their papers against) while the other half did not. In the second experiment, all students received general writing instruction, but the treatment group also received detailed instruction in the use of a writing-skills rubric that formed the basis for evaluating students' performance on written assignments. In both cases, the post-treatment difference between groups was small but showed an improvement in the specific skills taught, while showing no change or slightly decreased performance in related skills that were not explicitly taught. We conclude that limited interventions of the sort we were able to engage in were not sufficient to bring about a meaningful improvement in student performance, but the preliminary evidence suggests that the use of rubrics as a pedagogical tool, combined with repeated small-scale interventions, may be effective if targeted and/or repeated across a course or curriculum.