All Arabic-speaking children grow up in diglossia. They use a spoken Arabic vernacular (SpA) for everyday speech but Standard Arabic (StA) for reading/writing. The current study reports a pilot diglossia-centred intervention among Palestinian-Arabic-speaking kindergarteners (N = 290; mean age 64.52 months). The study examines the effectiveness of an intervention programme grounded in the linguistic distance between StA and the children's SpA vernacular in producing gains in children's metalinguistic awareness in SpA and in StA. The intervention programme lasted for 4-5 weeks and followed two principles: (a) train metalinguistic awareness first in SpA and then in StA; (b) train linguistic representations in StA as a basis for metalinguistic awareness in StA. Using syllable blending to test phonological awareness and morphological analogies to test morphological awareness, the study produced preliminary experimental evidence for gains in metalinguistic awareness in the intervention group that were significantly larger than those observed in the control group, in SpA and StA. The results, though preliminary, support the effectiveness of diglossia-centred interventions in promoting pre-school children's metalinguistic awareness in a sociolinguistic context in which two language varieties are used within the same community.