| This explanatory sequential mixed-methods study examined how the language used in pre-speaking discussions (PSDs) relates to Iranian EFL learners' oral language performance (OLP), willingness to communicate (WTC), and linguistic self-confidence (LSC). Thirty-six male B2-level learners in a university speaking workshop took part. Three PSD language modes were implemented across five intact discussion groups: L1-only (Turkish n = 7, Kurdish n = 6, Arabic n = 7), L2-only (English, n = 9), and mixed L1–L2 (n = 7). Over 10 sessions, each group completed a 10-minute PSD in its assigned mode before a 20-minute English speaking task. WTC, LSC, and OLP were measured before and after the intervention. One-way ANCOVAs on post-test scores, controlling for pre-test scores, showed significant between-group effects for WTC, F(4, 30) = 4.56, p = .005, partial η² = .38, and LSC, F(4, 30) = 6.21, p = .001, partial η² = .45, but not for OLP, F(4, 30) = 1.84, p = .148. Exploratory within-group comparisons showed significant LSC gains in all four groups whose PSDs involved the first language (gav = 0.34–0.55) and a significant WTC gain in the mixed-language group (gav = 0.34); the English-only group changed significantly on neither affective outcome, and no significant OLP change was detected in any group. Interviews with 25 participants indicated that L1-involving PSDs were experienced as reducing anxiety, supporting brainstorming, and increasing readiness to speak. Because the groups were intact and participants were not randomly assigned, the findings are interpreted as associational rather than causal. |