Children and youth have been engaging in climate action in significant numbers in recent years. They have engaged in protests in the streets, as well as dialogue with governments and intergovernmental organisations. In recent years they have been taking climate cases against governments with the aim of decreasing emissions in an effort to mitigate the climate crisis. In this article, we examine this action through the lens of child/youth participation. We begin by examining how the right to a healthy environment has developed. We then consider how participation rights for children have developed since the advent of the UN Convention on the Rights of the Child and, in particular, how the Lundy model frames children’s participation. Drawing on various examples of child/youth climate action, we apply the concepts of space, voice, audience and influence. We also consider the “postpaternalism” in different types of participation in environmental initiatives.