System 123 (2024) 103321 Available online 6 May 2024 0346-251X/© 2024 Elsevier Ltd. All rights reserved. Conceptualization and measurement of foreign language playfulness via exploratory structural equation modeling Kaiqi Shao a, b, * , Elyas Barabadi c , Majid Elahi Shirvan c , Tahereh Taherian d , Mohsen Rahmani Tabar e a School of Foreign Studies, Northwestern Polytechnical University, Xi’an, China b Department of Foreign Languages, Hangzhou Dianzi University, Hangzhou, China c Department of Foreign Languages, University of Bojnord, Bojnord, Iran d Department of English Language, Yazd University, Yazd, Iran e School of Psychology, University of Canterbury, Christchurch, New Zealand A R T I C L E INFO Keywords: Playfulness Foreign language Measurement Exploratory structural equation modeling Positive psychology ABSTRACT The current research sought to conceptualize and measure foreign language playfulness (FLP), a recently developed construct in second language acquisition (SLA), through exploratory struc- tural equation modeling (ESEM), a recently introduced scale measurement approach. Using a sample of 208 Iranian undergraduate language learners, we employed a series of statistical techniques to examine the underlying structure, best fitting model, psychometric properties, measurement invariance, and factor correlation of a new measure of FLP. Findings showed that bifactor EFA, compared with EFA, provided better representation for the underlying structure of the FLPS. Multiple model comparisons indicated that the bifactor ESEM model had a more satisfying representation of the FLPS than the other models (CFA, bifactor CFA, and ESEM). Cronbach’s α and omega (ω) demonstrated that the FLPS is a reliable instrument. The bifactor ESEM model of the FLPS was also invariant across genders. Finally, factor correlation in ESEM exhibited a more accurate reflection of the association between the two factors (intellectual playfulness and other-directed playfulness) of the FLPS. The results were discussed by high- lighting the importance of using ESEM to validate psychological constructs in SLA. 1. Introduction Playfulness is a psychological construct that refers to individuals’ propensity to “frame and reframe everyday situations in a way such that they experience them as entertaining, and/or intellectually stimulating, and/or personally interesting” (Proyer, 2017, p. 114). Playful students can turn different academic situations into something which is personally interesting and intellectually stim- ulating, hence facilitating their learning and performance (Proyer, 2017). The relevance of this line of research to the field of SLA is immediately apparent given that SLA is a long-term process necessitating learners’ positive characteristics such as playfulness to overcome constant challenges and uncertain learning environment. Notwithstanding the perceived importance of this variable for SLA and the bulk of studies documenting the prominence of playfulness in psychology and sociology (e.g., Cheng et al., 2021; Proyer, 2014; * Corresponding author. School of Foreign Studies, Northwestern Polytechnical University, Xi’an, China. E-mail addresses: shaokaiqi@aliyun.com (K. Shao), elyas.ba1364@gmail.com (E. Barabadi), elahishmajid@gmail.com, elahi@ub.ac.ir (M. Elahi Shirvan), taherian87@yahoo.com (T. Taherian), Mohsen.rahmanitabar@pg.canterbury.ac.nz (M. Rahmani Tabar). Contents lists available at ScienceDirect System journal homepage: www.elsevier.com/locate/system https://doi.org/10.1016/j.system.2024.103321 Received 9 January 2024; Received in revised form 24 April 2024; Accepted 25 April 2024