Purpose: This study aims to examine factors that affect the effectiveness of transfer of English language training to the workplace. It investigates the effect of trainee characteristics, training design and work climate on the training transfer to job performance in hospitals in Thailand. Design/methodology/approach: The quantitative method was adopted in this study. The conceptual framework was developed from Lim and Morris' three-factor model, namely, trainee characteristics, training design and work climate. A total of 378 valid responses from staff of seven hospitals in Thailand were collected from surveys. Findings: The findings suggest that training transfer depends more on trainees' psychological state (affective response and self-efficacy) than extrinsic factors. Nearly every aspect of training design could affect training transfer, except trainer effectiveness. This could be related to the particular context of training and the trainees' prior experience. Work climate factors had the strongest overall effect, with peer and supervisor feedback, compensation and incentives and transfer opportunities being significant. Originality/value: This study proposes that training design and work climate-related factors deserve more attention than what they have received previously. This study is significant because of the limited empirical evidence for English training transfer outcomes, and the under-examined role of English as a lingua franca in the business world. The findings can help organisations refine training designs and adjust the work environment to improve training outcomes.