Research indicates that work-integrated learning (WIL) experiences enable students to develop both generic and work skills as well as helping students identify their future academic and career directions. This study used pre- and post-survey instruments to evaluate the effectiveness of a WIL placement to develop work skills of students in different academic programs of a university in Thailand. This research was based on an Australian work skills development framework model. The analyses of the pre- and post-survey results on 584 co-op students indicated notable changes in student work skills performance after entering the workplace. The program difference in work skills is significant between the groups when ANCOVA test was applied using pretest-placement as covariates. The positive learning gains suggest that WIL enables students to acquire confidence, building work skills particularly in "initiative/motivation to engage", and attain the ability to self-reflect on whether they have contributed to improved productivity in the workplace.