A testing effect occurs when a learner performs better on a retention test after studying the material and taking a practice-retention test than after studying the material twice. In the present study, 282 participants watched a narrated animation about lightning formation and then watched the presentation again (restudy), took a practice-retention test (practice-retention), or took a practice-transfer test (practice-transfer). First, the testing effect was replicated with multimedia material, such that the practice-retention group outperformed the restudy group on a delayed retention test. Second, a testing effect was found for taking a practice-transfer test, such that the practice-transfer group outperformed the restudy group on a delayed transfer test. Third, the results supported a transfer-appropriate processing explanation of the testing effect, in which the practice-retention group outperformed the practice-transfer group on delayed retention but the opposite pattern was obtained on delayed transfer. (Contains 3 figures, 1 table, and 5 footnotes.)