As populist leaders leverage disparities across geographic and language communities, democracies are threatened by an increasingly divisive political climate that compromises public discussions. This study evaluates how the basic communication strategy of utilizing local languages in information campaigns can help overcome divides by encouraging engagement and discussions. We conduct a field experiment to assess whether using the four most prevalent languages in the Philippines (Cebuano-Bisaya, Ilonggo-Hiligaynon, Ilokano, and Waray-Samarnon) can increase engagement in online materials for targeted linguistic groups. Through split-testing on Facebook, we find evidence that local language materials are more likely to catch the attention of the audience and increase engagement. Qualitative validation shows that local language use is an effective tool to build self-efficacy for linguistic groups to join in on national conversations, and serves as an identity marker to evoke a sense of pride and community. These findings open opportunities for evidence-guided social media campaign strategies.