Current research indicates learning effort to be an important determinant of success in learning, yet the field of education lacks an adequate scale for quantifying foreign language learning effort. The Foreign Language Learning Effort Scale (FLLES) has been developed to measure the effort levels of tertiary-level foreign language learners. Data was collected from students learning English at various public and foundation universities in Ankara in Turkey. An item-pool was initially created and expert opinion was taken to ensure content validity. Next, exploratory factor analysis was carried out over 628 students, which yielded a 4-factor model that was then tested for construct validity and verified using confirmatory factor analyses over both the pilot sample and an independent sample consisting of 701 participants. The internal consistency and reliability coefficients for FLLES and its dimensions were calculated for both the pilot and replication samples. In addition, a test-retest reliability analysis was carried out over 64 students. The scale was further assessed for predictive, convergent, and discriminant validities. The results of the research show the FLLES to be a valid and reliable instrument consisting of 17 items and four dimensions.