This conceptual paper explores the intersection of human rights, children's rights, and peace education, and language education. Languages, communication, and dialogue play a crucial role in international understanding and cooperation towards human rights, children's rights, and peace. This contribution recognizes communicative competence as inclusive of ideology-critical abilities (Delanoy, 2017) and begins by arguing that for students to become "agents of change and protagonists of their future" (UNESCO, 2024, p. 5), their communicative agency must be considered an essential aspect of transformative education. The discussion will focus on the field of English (as a "foreign," second or additional) language education, as English is one of the lingua francas used in global discourses on human and children's rights, peace, and sustainable development. This paper will take a dialogue-based and interdisciplinary approach and will be developed in two steps: first, it explores how language education can provide a unique lens for educating on human and child rights, peace, and social sustainability. Second, it explores the dimensions by which a critical approach to language education for peace can promote transformative communicative agency in the pursuit of social objectives. It will argue that through its focus on languages, cultures and literatures, the "foreign" language classroom is uniquely positioned to engage with the stories and people of the world; further, a critical language education for peace can empower learners to take communicative action for their own rights and to protect the rights of others.