Bilingual adults are faster in reading cognates than in reading non-cognates in both their first language (L1) and second language (L2). This cognate effect has been shown to be gradual: recognition was facilitated when words had higher degrees of cross-linguistic similarity. The aim of the current study was to investigate whether cognate facilitation can also be observed in bilingual children's sentence reading. To answer this question, a group of Frisian-Dutch bilingual children (N = 37) aged 9-12 years completed a reading task in both their languages. All children had Dutch as their dominant reading language, but most of them spoke mainly Frisian at home. Identical cognates (e.g., Dutch-Frisian boek-boek 'book'), non-identical cognates (e.g., beam-boom 'tree'), and non-cognates (e.g., beppe-oma 'grandmother') were presented in sentence context, and eye movements were recorded. The results showed a non-gradual cognate facilitation effect in Frisian: identical cognates were read faster than non-identical cognates and non-cognates. In Dutch, no cognate facilitation effect could be observed. This suggests that bilingual children use their dominant reading language while reading in their non-dominant one, but not vice versa.