Sweden is nowadays a multicultural society. This also means that Swedish social services increasingly come in contact with ethnic minority families. This study aims to examine the ways in which social workers consider and talk about the clients’ ethnic background in relation to child welfare cases. Further, the aim is to reveal the ways in which ethnicity is done and reproduced in social work practice. To reach this goal, a qualitative vignette study is applied. The research participants, Swedish social workers in the field of children and family, were invited to focus groups interviews and asked to react to vignettes constructed around three notices of child abuse. Different focus groups received vignettes with different names of the child: Erik represented ethnic majority name, while Ali represented ethnic minority name. The application of qualitative content analysis resulted in the differentiation of the following themes: worry, description of the case and construction of the family. The results in this study demonstrate that depending on the child’s name, social workers viewed the case and the family differently and ascribed different levels of worry to their respective cases. These findings are discussed through the perspective of social constructionism and the concept of ethnicity as being socially constructed to demonstrate the mundane ways in which ethnicity is constructed in social work practice. This study emphasizes the complexity and challenges that may accompany social work practice with ethnic minority families.