The present, multi-method (methodological triangulation), case study aimed to investigate whether it is possible to obtain a differential diagnosis between the speech problems derived from bilingualism, and the developmental speech problems of an Albanian eight-year-old boy who attended a public primary school in Greece. Although there existed multiple possible factors that could cause and worsen the speech difficulties, such as developmental and health problems in the child's early years, as well as a deprived social environment, the findings supported that the aforementioned differential diagnosis could be achieved. However, the construction of IQ, psycholinguistic and school performance standardized tests for bilingual children will help minimize the difficulties of a valid and completed speech disorders diagnosis, in order for all these children to have the benefit of the appropriate intervention and remediation programme.