Time management is regarded as an important prerequisite for effective and efficient learning in higher education. However, university students’ time management frequently proves to be deficient, especially with freshman students, who can therefore benefit from appropriate time management interventions. The aim of this study was to compare the effects of an intervention focused on imparting time management knowledge with those of an intervention focused on time management practice. We conducted an experiment with N = 118 university students who took part in a course over the duration of one semester. Participants with a time management deficit at the beginning of the semester (n = 88) were randomly assigned to one of three experimental conditions: (a) time management knowledge, (b) time management practice, (c) control group. Exam scores at the end of the semester were considered as an indicator of participants’ academic performance. The results showed significant time management improvements for both time management intervention groups, but the time management practice group appeared superior. Academic performance was better in the time management practice group also, although the results were inconsistent. The effect of time management practice on academic performance was mediated by students’ time management skills.