Developmental dyscalculia is a specific learning disability that is described as a heterogeneous and persistent cognitive disorder. Given the need to detect and intervene as early as possible to minimise its effects, teachers' knowledge about symptoms, characteristics and effective intervention strategies in dyscalculia is essential. Given the lack of research about this topic and measures to evaluate teachers' knowledge, this study aims to present a literature-based measure to evaluate knowledge about developmental dyscalculia and to investigate the predictors of this type of knowledge. Data were collected from a sample of 175 primary school teachers. The measure presented adequate psychometric properties. Teachers' personal characteristics such as age and gender did not predict their knowledge about dyscalculia. Being a Special Education teacher predicted a higher knowledge of intervention strategies in dyscalculia and having heard about dyscalculia predicted higher knowledge about not only intervention strategies but also dyscalculia characteristics. The data are discussed, and suggestions for further studies are presented.