Research demonstrated that oral explaining to a fictitious student improves learning. Whether these findings replicate in written contexts, and whether instructional explaining is more effective than other explaining strategies such as self-explaining is unclear. In two experiments, we compared written instructional explaining to written self-explaining, and also included written retrieval and a baseline control condition. In Experiment 1 (N = 147, between-participants-design, laboratory experiment), we obtained no effect of explaining. In Experiment 2 (N = 51, within-participants-design, field-experiment), only self-explaining was more effective than our control conditions for attaining transfer. Self-explaining was more effective than instructional explaining. A cumulating meta-analysis on students’ learning revealed a small effect of instructional explaining (conceptual knowledge: g = 0.29, transfer: g = 0.22), which was moderated by the modality of explaining (oral explaining > written explaining). These findings indicate that when students writing explanations are better off self-explaining than explaining to a fictitious student.