Child rights research has increased since the adoption of the Convention on the Rights of the Child (CRC) in 1989. Reviews of the research has indicated a lack of criticality and a reluctance to interrogate or challenge dominant views. Some scholars argue that this results from under theorisation, whereas other maintain that theorisation is abundant. The paradox suggesting that children's rights research can be both abundant and deficient in theory calls for a thorough discussion about theorisation. This systematic review engages in this debate by exploring what is positioned as "theory" in educational children's rights research, and what function theory has. Analysis determined that alignment with established theoretical approaches is uncommon. Previous research literature is instead often positioned as theory, mostly in combination with policy, law or an established theory. Main functions of theory are to construct the object of study and to provide analysis support. Some uses of theory appear to be more powerful than others.