Research has consistently shown that inquiry-based learning can be more effective than other, more expository instructional approaches as long as students are supported adequately. But what type of guidance is adequate, and for whom? These questions are difficult to answer as most previous research has only focused on one type of guidance and one type of learner. This meta-analysis therefore synthesized the results of 72 studies to compare the effectiveness of different types of guidance for different age categories. Results showed facilitative overall effects of guidance on learning activities (d = 0.66, 95% CI [0.44, 0.88]), performance success (d = 0.71, 95% CI [0.52, 0.90]), and learning outcomes (d = 0.50, 95% CI [0.37, 0.62]). Type of guidance moderated the effects on performance success but not on the other two outcome measures. Considerable variation was found in the effects of guidance on learning activities, but the relatively low number of studies do not allow for any definitive conclusion on possible age-related differences.