<![CDATA[Language environment constitutes a fundamental pillar in second language acquisition, including learning Arabic within Islamic boarding schools (pesantren). The variation of input, the intensity of interaction, and the consistency of practice collectively form the primary scaffolds for developing students’ communicative competence. In the pesantren context, these elements are both pedagogical tools and part of a broader cultural and spiritual ecosystem that shapes language use in structured and spontaneous ways. When effectively designed and managed, this dual ecosystem has the potential to accelerate the process of Arabic acquisition significantly. This article examines the dynamics of the Arabic language environment in pesantren and its relationship with the core dimensions of input, interaction, and output. A qualitative case study design was employed, with participants selected purposively to capture diverse language learning experiences. Data collection involved observation, in-depth interviews, and document analysis, which were systematically analysed using Krippendorff’s content analysis framework, covering data reduction, thematic classification, interpretation, and conclusion drawing. The findings point to two interrelated categories of the Arabic language environment. The first is the formal environment, encompassing structured classroom learning such as maharat al-qirā’ah, al-kitābah, al-istimā‘, and al-kalām. This environment facilitates the acquisition of linguistic accuracy by aligning input and teacher–student interaction with grammatical and syntactical norms. The second is the informal environment, which emerges in daily activities such as muḥādathah, ilqā’ al-mufradāt, maḥkamat al-lughah, and muḥāḍarah. Unlike the formal setting, the informal environment privileges fluency and spontaneity, enabling learners to transform theoretical knowledge into practical communicative competence. These findings underscore that the synergy between formal and informal environments is both complementary and transformative: it enriches input, strengthens interaction, and ensures that output is accurate and communicatively meaningful. The implication is clear: success in Arabic language learning within pesantren is primarily determined by how comprehensively the language environment is designed to integrate theoretical instruction with authentic communicative practice.]]>
