College students participated in a study on the "psychology of note taking" during which they took notes on video content and later completed a multiple-choice test on the material. Researchers assigned 71 participants to either the ringing condition (the video was disrupted by a ringing cell phone) or the control condition (no cell phone rings disrupted the video). The hypothesis that the cell phone rings would impair performance was confirmed. Compared to the control group, participants in the ringing condition performed significantly worse on the disrupted test items and were less likely to include the disrupted information in their notes. Citing empirical evidence of academic impairment in course syllabi may improve regulation of cell phone use in the classroom. (Contains 2 notes and 1 table.)