Self-regulation (SR), widely studied in educational psychology, remains underexplored

in Applied Linguistics and in English as a Foreign Language (EFL). This study investigates

EFL undergraduates’ self-regulatory capacity of intentional vocabulary learning (SRC-IVL)

by employing an exploratory sequential design across two distinct phases. The study aimed to

understand the extent to which learners use the different self-regulatory capacities in their

intentional vocabulary learning and the factors influencing their general self-regulatory

capacity of intentional vocabulary learning (SRC-IVL).

The qualitative phase involved in-depth interviews with fourteen participants who

explained variations, including occasional limitations in their use of the different self-regulatory

capacities. Additionally, interviews revealed a variety of psycholinguistic, linguistic

and contextual factors influencing SRC-IVL. These findings informed the development of a

questionnaire which involved 550 participants in the subsequent quantitative phase. The

quantitative analysis explored differences in learners’ self-regulatory capacities across

different socio-demographic variables, such as age group, gender, English levels, and major

groups, using one-way MANOVA. The results showed few differences among younger age

participants and learners at the introductory English level who exhibited higher SRC-IVL. The

study also examined some psycholinguistic factors and their relationships with SRC-IVL using

Structural Equation Modelling (SEM). One of the key findings is that perseverance of effort

and a growth mindset play an important role in predicting learners’ SRC-IVL, both directly

and indirectly.

The results highlight the importance of learners’ psychological states as key factors in

facilitating SRC-IVL among EFL learners. One of the main implications is that language

learners need support in developing their self-regulatory capacities in order to achieve

successful language learning. These findings also offer valuable insights to guide future

research on self-regulatory capacity in language learning and how it can be more effectively

fostered in EFL contexts.