AbstractI argue that participatory action research (PAR) is a valuable means by which to advance citizen social science, not by researching with and on adults, but with children and young people (CYP). Given the right opportunities, using child-friendly and child-centred research methods, CYP can be credible, competent contributors to social science, including the digital environment. The foundational goals of PAR are empowerment, transformation, and enfranchisement of the traditionally marginalised, and none are more universally and structurally marginalised than CYP. Using a child rights argument, I explain why CYP continue to be excluded from research and why there is still so much scepticism that CYP are credible contributors. One reason is childism, a system of oppression, prejudice, and discrimination against CYP on account of their perceived status as not yet human and not fully rational beings. Childism entails the belief that adults are automatically superior to children. I argue further that CYP’s participation in postdigital social science research enacts the entitlements in Convention on the Rights of the Child (CRC), even though state parties, having ratified this landmark convention, find it very challenging to do more than simply laud its aims. Using three case studies of CYP’s contribution to research and human rights activism, I make the case that they are expert knowers of their own social and digital experiences and have the skills and insights to examine their social worlds in ways that adult researchers too easily overlook, downplay, or simply ignore. As importantly is that CYP are expert users of digital and social media. Their epistemic and ontological experiences as users, creators, contributors, and disseminators of content, and as targets of malign actors, must be included in any research, policy, or law.