This paper presents a quantitative analysis of the variable use of the subjunctive which constitutes a notable "fragile zone" in the spoken French of advanced L2 learners. A comparative approach is adopted to consider the relative impact of naturalistic and instructed L2 exposure in the case of our learner-participants who were Irish university learners in both a classroom and study abroad context. The findings presented attempt to illuminate the difficulty that use of the subjunctive poses to the learners, whereby their minimal use of this form, irrespective of their context of acquisition, is lexically restricted to the occurrence of "falloir" in the matrix clause, although the learners do produce other subjunctive-conditioning verbs and conjunctions expressing subordination. The findings are discussed in terms of their pedagogical and acquisition implications. (Contains 1 table and 7 notes.)