Self-regulation has become a widely discussed subject in education as it facilitates learners' ability to master their own learning. The purpose of the present study is to examine the psychometric properties of self-regulation in second language learning via Rasch measurement. A total of 528 high-school students from an East Asian country participated in the study, and the Self-Regulating Capacity in English Language Learning (SRClang) Scale was used as a self-report instrument. The results suggest that self-regulation in second language learning as measured by the SRClang Scale does not appear to be unidimensional. Based on item-model fit statistics, several items in the SRClang Scale may need to be revised or removed. Nonetheless, the response categories in the SRClang Scale function well as intended, and the scale can reliably separate items and persons based on their difficulty levels and ability trait levels, respectively. Overall, the SRClang Scale serves as an appropriate measure of self-regulatory capacity in second language learning.