<p>Dispositional flow (DF) refers to an individual’s propensity to experience flow, with high DF being a central characteristic of the autotelic personality. Despite the growing call for including more noncognitive and positive factors of individual difference in SLA research, the construct of DF in language learning has remained an “uncharted territory”. Against this backdrop, this exploratory study investigates the levels, characteristics, possible correlates of L2 DF, and its correlation with L2 proficiency among Chinese EFL undergraduates. A total of 1767 undergraduates from different parts of China completed an online questionnaire that included the Chinese version of the short Dispositional Flow Scale-2 (CSDFS) and a set of sociodemographic and L2 learning background items. The main findings are as follows: The majority (about four-fifths) of learners are generally prone to L2 flow. Latent profile analysis of the valid sample (N = 1241) delineates three subgroups: autotelic-oriented L2 learners (approximately one-fifth), characterized by frequent experience of all nine flow characteristics in L2 learning; their non-autotelic counterparts (approximately one-fifth) possibly with minimal L2 flow occurrence; and a moderate majority (approximately three-fifths) who possess the potential for dynamic transformation between the two orientations. The discriminant validity gradient reveals L2 DF as a hierarchical construct, anchored centrally in Sense of Control, with Transformation of Time being negligible. Additionally, regression analyses indicate a significant positive association between L2 DF levels and standardized English proficiency scores (CET-4 and the English exam on the College Entrance Examination). Furthermore, chi-square tests identify both family involvement and motivational orientation (intrinsic/extrinsic) as key correlates of L2 DF levels. The role of family involvement was further examined by follow-up qualitative responses.</p>