Phonological Vocabulary Size: Validating Measurement and Tracking Development Among Chinese L2 Learners

This study aims to develop a phonological vocabulary size test for Chinese L2 learners, provide validation evidence for the instrument, and track the development of phonological vocabulary size using a longitudinal design. A Chinese Phonological Vocabulary Levels Test (CPVLT) was developed and administered to 72 Chinese L2 learners in post‐secondary institutions. Rasch analyses were employed to evaluate its properties. The results show that the test presents an adequate spread of difficulty, with most items displaying a good fit to the Rasch model. Unidimensionality was supported, with 78% of the raw variance explained by person and item aspects. To examine developmental change, nine participants from the initial sample completed the CPVLT and participated in follow‐up interviews four times over the course of a semester. The complex dynamic systems theory (CDST) approach was adopted to interpret the developmental trajectories. The results reveal varied developmental patterns, including continuous decline, continuous progress, and off‐and‐on progress, which reflect the changing distribution of internal and external learning resources, such as time devoted to learning Chinese. The study provides a valid and reliable instrument for measuring Chinese learners’ phonological vocabulary size and sheds light into vocabulary development, which involves not only gains but also attrition.