English as a Lingua Franca (ELF) has become the primary medium of international communication, yet language assessment practices continue to privilege native-speaker norms that misalign with multilingual communication realities. This study addresses the critical need to redefine oral assessment frameworks for ELF contexts, particularly in Japanese universities where English increasingly serves as a cross linguistic tool among diverse multilingual speakers rather than as an endpoint modeled on native-speaker competence. Using a two-phase qualitative design, this study analyzed seven naturally occurring dialogues (10,030 words, ~ 2.35 h) from the English as a Lingua Franca in Japan (ELFJ) Corpus involving Japanese and non-Japanese English speakers. Conversation Analysis and Interactional Sociolinguistics were employed to identify successful ELF communication strategies. Document analysis of Cambridge English assessment frameworks was conducted to examine how existing competency descriptors could be reconceptualized for ELF-aligned (context-valid) assessment contexts. Nine distinct ELF communication strategies emerged as essential for successful multilingual interaction: negotiation of meaning, self-initiated communication strategies, simplification, repair, lexical innovation, code-switching, accommodation, turn-taking management, and collaborative construction. Analysis of existing assessment frameworks revealed three critical inadequacies: native-speaker norm orientation, limited recognition of strategic communication, and absence of multilingual resource recognition. Based on these findings, a reconceptualized framework with four ELF-informed criteria is proposed for future validation: Intelligibility and Clarity, Strategic Communication, Interactional Effectiveness, and Multilingual Resourcefulness. This study suggests that ELF-aligned (context-valid) oral assessment requires fundamental reconceptualization beyond superficial modifications to existing frameworks. The proposed ELF-informed assessment criteria prioritize communicative effectiveness and strategic flexibility over adherence to native-speaker norms, potentially offering a more valid and equitable approach to evaluating multilingual speakers’ English proficiency pending empirical validation. These findings have significant implications for language testing policy and practice in increasingly multilingual educational contexts across Asia and globally.