This chapter critically reviews theories of assimilation, acculturation, integration, and ethnicity in relation to newer-generation Korean New Zealanders. It traces shifts from classical assimilation to segmented assimilation and pluralist models, highlighting their limitations in capturing the complex identity negotiations of migrant youth. To address these gaps, the chapter proposes an interdisciplinary framework combining neo-assimilation theory, transnationalism, and cultural hybridity. It considers both structural factors—such as multicultural policy, racial hierarchies, and biculturalism—and agential ones, including identity negotiation and re-ethnicization influenced by transnational ties and Korean pop culture (Hallyu). Analyzing how these forces interact, the chapter provides a theoretical lens for understanding the diverse acculturation experiences of Korean New Zealander youth and offers a more nuanced view of identity and belonging in multicultural New Zealand.