Subject relative clauses (RCs) have been shown to be acquired earlier, comprehended more accurately, and produced more easily than object RCs by children. While this subject preference is often claimed to be a universal tendency, it has largely been investigated piecemeal and with low-powered experiments. To address these issues, this meta-analysis follows an established and rigorous scientific method to test the generalizability of the subject preference in RC acquisition by evaluating the collective evidence. While the results show a significant crosslinguistic subject preference, there is a large amount of heterogeneity in the data. The manifestation of this subject preference may not be uniform across languages, depending on typological properties such as language headedness, RC headedness, and main clause similarity. The true impact of these features, however, requires research on more typologically diverse languages.