Writers who read, think, and write across languages need tailored support to navigate the complexities of crosslingual writing. Despite interest in pedagogical translanguaging and the rehabilitation of translation in language teaching, crosslingual writing remains underexplored as it stands at the margins of established disciplinary domains such as additional language instruction, writing pedagogy, and translator education. This Element argues that crosslingual writing is not only an essential skill for plurilingual communication, but also a powerful tool for language and writing development and deeper learning. Situating crosslingual writing within the trans/plurilingual turn and combining theoretical, empirical, and pedagogical insights from language (in) education, writing instruction, and translation studies, this Element identifies tools, strategies, and digital literacies for AI-powered crosslingual writing. It further explores how crosslingual writing can be systematically integrated into language curricula, offering practical strategies for pedagogical task design, scaffolding activities, and crosslingual writing assessment.