This study examines English proficiency differences between Mondok (full-time Islamic
boarding) and Nyolok (daily commuting) students in an Islamic vocational Pesantren in
Jember, Indonesia. Using mixed-methods with 40 female students (20 each group), tests
revealed Mondok students scored significantly higher (68.50 vs. 63.25; p = .038). Despite
this 5.25-point difference, both groups achieved intermediate proficiency through distinct
pathways—demonstrating Complex Dynamic Systems Theory's principle of equifinality.
Qualitative data showed Mondok students, despite technological constraints, developed
adaptive strategies like peer learning and utilized limited "kiriman" time effectively. In
contrast, Nyolok students with technological access struggled with consistency and
speaking anxiety due to less structured environments. The findings illustrate how different
environmental conditions within the same institution trigger unique adaptive patterns,
highlighting CDST's value in explaining non-linear language development in Islamic
educational contexts and offering practical implications for differentiated instruction in
vocational Pesantren.