This multiple case study investigated pedagogical decisions in encountering challenges in pre-service teachers' integrated-skills instruction and the underlying factors influencing their different responses to the challenges during their overseas Chinese teaching practice programme. Two cohorts (n=8) of pre-service teachers were involved in this study when they participated in the teaching practice programme for 15 weeks at seven K-12 schools in North and Central Thailand. In this study, data collected through semi-structured interviews and documents were analysed. Four challenges emerged in teacher trainees' implementation of integrated-skills instruction: (1) students' inability to understand target language instruction, (2) low level of motivation and disengagement in communicative tasks which required multiple skills, (3) unsatisfactory performances in form-focused teaching, and (4) classroom disciplinary issues. The findings demonstrate that the contextual support from local schools appeared to be the main contributing factor that influenced these trainee teachers' pedagogical decisions in their integrated-skills instruction, which was mediated by students' performance and behaviours in class. In schools with sufficient support, which acted as solutions to challenges, the pre-service teachers reported consistent use of the integrated-skills instruction; however, in schools that lacked a supportive environment, the challenges remained unsolved and there was a shift from predominant integrated-skills instruction at the early stage to segregated-skills form-focused teaching for better classroom management in the latter phase. The study highlights the critical role of contextual factors in teachers' decision making when confronted with challenges in integrated-skills instruction.