Short-term Christian overseas volunteer trips, also known as short-term mission trips (STMs), have become increasingly prevalent (Howell & Dorr, 2007). However, research on these programs has been limited. This quasi-experimental study adds to the literature by quantitatively measuring the effects of an STM from Singapore to Thailand. STM recipients’ ( n = 44) self-esteem and readiness for self-directed learning (RSDL) were compared across timepoints – pre-test, post-test, follow-up – and with a control group ( n = 50). It was hypothesized that recipients would experience an increase in self-esteem and RSDL such that their scores would be higher than the control group post-STM. Results provide partial support for the hypotheses; while improvements among recipients were either not significant (for self-esteem) or not long-lasting (for RSDL), recipients had higher scores than the control group post-STM. This suggests that STMs have some, albeit limited, positive effects. Recommendations for promoting greater and longer-lasting effects are offered.