Generative AI (GenAI) technology is transforming the landscape of language teaching and learning and has attracted considerable attention from researchers and educators in the field of second language (L2) education. Research has shown that, when used appropriately, GenAI can support students throughout the writing process, provide high-quality feedback on written work, and facilitate the assessment of L2 writing. This Element presents five innovative topics that the co-authors have explored: (1) student-GenAI interaction during the writing process; (2) collaborative processing of GenAI-generated feedback; (3) GenAI-supported teacher feedback; (4) the potential of GenAI for L2 writing assessment; and (5) teacher education for the effective integration of GenAI in L2 writing instruction. By synthesizing current research and practical applications, this Element aims to inspire researchers, practitioners, and graduate students to further investigate the role of GenAI in L2 writing contexts.