Abstract: Children’s ‘rights to the city’ and ability to participate in urban decision-making are critical to filling the needs and aspirations children have for play, development, exploration, healthy lifestyles and social/physical belonging. Children’s engagement (or disengagement) with the city also shapes the relationships and civic responsibilities that children develop towards the city. CATCH/iMATCH is a three-year research project examining the influence of the built, social and policy environments on children’s independent mobility and active travel in Australia. As an extension to the main CATCH/iMATCH project, an intensive ‘Citizen Kid’ Planning Group (CKPG) was established in Melbourne. The CKPG brought 13 children and 9 adult practitioners together to co-plan two neighbourhood public plazas, aiming to make them better for children and to explore children’s active citizenship and social connectedness ‘in situ’. The CKPG also sought to understand what practitioners require by way of tools/frameworks, processes, knowledge and skills to feel more confident in facilitating children’s involvement in planning processes. This paper presents the findings of the ‘Citizen Kid’ Planning Group and explores some of the lessons for both research and for planning practice, that have been highlighted in this action research case study. Findings from the broader CATCH/iMATCH research augment the discussion about how children engage with urban planning and how planners can better understand children’s ‘voice’ in planning matters and play a positive role in shaping the next generation of urban citizens.