The paper presents the first comprehensive look at the language development of Romani-speaking children from resource-poor Roma communities in several European countries. 250 participants aged 3- to 10-years participated. The experimental tasks assess knowledge in eight key areas of grammar and morphology, including fast mapping of novel items. The special properties of Romani allow new insights on long distance wh-movement and possessive agreement, and the data question the universality of other distinctions in passives and wh-movement from complements. The results demonstrate that the Roma children as a group are as proficient in their primary language as children in other countries, despite massive economic deficits and lack of parental education. This is important because Roma children are massively overrepresented in special education and "special schools" especially in Eastern Europe, and one contributing factor is their inadequate skill in the state language of their domicile.