Children have been shown to be one of the most economically vulnerable groups within the South African context. We examine and decompose the dynamics of child poverty in South Africa over the period 2008–2012 in order to arrive at a better understanding of the nature and causes of child poverty, and specifically persistent poverty over time. We use the framework of an asset poverty line first developed by Carter and May (World Development, 29(12), 1987–2006, 2001) and longitudinal data from the National Income Dynamics Study in order to identify those children in households that are in structural poverty with an asset base which is too low to escape poverty in the long run. We find that almost 40 % of the children in our sample found themselves in this structural poverty trap between 2008 and 2012. As expected, these children have suffered as a result of this deprivation, even in comparison to their peers who have also been poor over the period, but were living in households with access to more assets. We conduct some preliminary investigations into the potential causes of welfare changes over time. In line with previous work on the topic, we identify low initial levels of education, low asset-holdings, low initial employment and adverse household formation as possible causes of these poverty traps.