There is a dearth of information on cultural perceptions of children's language development for ethnic minorities in New Zealand to guide service provision. The current study explored differences across ethnicities in mothers' report of language concern and child language scores within a complex cultural, social, educational, and political context. Data from the antenatal and 54-month waves of Growing Up in New Zealand were utilized. At the 54-month wave interviews, 5,053 mothers were asked if language concerns had been raised and to rate their child's main language proficiency along with other measures. Logistic regression models (including influencing variables) indicated Chinese, Indian, and other Asian mothers were less likely to report language concern, whereas Māori, Pacific, other Asian, and Middle Eastern, Latin American, and African children were more likely to score low on the language measure. Higher maternal education was associated with higher child main language scores, but not with language concerns. Child multilingualism was not associated with low language scores, and these mothers were less likely to raise concern. This study demonstrated differences by ethnicity in mothers' language concern and child main language scores, which are likely to affect access to speech-language pathology services, as these typically rely on parent concern being expressed. Cultural bias in the language measure may also be present. Further research is needed to ask ethnic communities their views on culturally appropriate ways to identify children with communication needs and to develop culturally safe services.