Although the concept of assessment as learning has important educational and practical implications, the utilisation and creation of contexts for assessment as learning in early childhood education are contemporary issues that need to be clarified. The overall goal of this work is to reconceptualise the role of the child portfolio as a tool for promoting assessment as learning in early childhood education. This theoretical framework provides some conceptual insights into children's agency in the learning and assessment process through the use of child portfolios. The main issue addressed is the progressive use of the child portfolio, which comprises observations of classroom experiences, documentation of these observations, revisiting learning experiences and a celebration of children's achievements. These aspects are discussed along with arguments that raise the question of how portfolios can act as catalysts for assessment as learning. This article further advocates that the multidimensional processes of creating a child portfolio may be considered a promising context for promoting autonomy, self-regulation, metacognition and reflection in early childhood education.