Roma, Gypsy and Traveller children across Europe experience high levels of disadvantage and have repeatedly been identified as a priority in European Commission policy documents, yet they are often missing or invisible in the large-scale statistical analyses of children at risk of poverty and deprivation that drive policy development and monitoring. In this paper we argue that population Censuses, and other administrative sources, many of which already record Roma ethnicity, are under-utilised as a source of robust and comparable data, allowing the scale, intensity and multi-dimensionality of the challenges facing Roma, Gypsy and Traveller children to be investigated and tracked. We illustrate this through the descriptive analysis of secure microdata from the 2011 Census of England and Wales, which included a pre-coded category for ‘Gypsy or Irish Traveller’ for the first time, and to which we add children identified as Roma. Disadvantage in each of four dimensions - housing, household economic activity, education and health - are examined in turn before computing a multiple deprivation count. Nearly a quarter of Roma, Gypsy and Traveller children in England and Wales aged under 19 are deprived on 3 or more dimensions, compared to just two per cent of other children. And conversely, only a small minority (15%) of Roma, Gypsy and Traveller children are not deprived in any dimension, compared to the majority (67%) of all other children. We conclude that data scarcity should no longer be used as an excuse for a lack of effective policymaking: it is both desirable and feasible to exploit Census data, as a step towards tackling the data deficit, and that the results can improve the design of child poverty and Roma, Gypsy and Traveller integration policies.