Background: Solving ill-structured problems is an important aspect in many professions, including the teaching profession. It is therefore appropriate to engage pre-service teachers in solving ill-structured problems. Aim: This study investigates the ill-structured problem-solving processes in an un-moderated asynchronous discussion for one group of pre-service teachers in Singapore. Sample: 21 pre-service teachers taking a post-graduate diploma teacher preparation course at the National Institute of Education, Nanyang Technological University, Singapore. The module in this study is a course entitled "Teaching and Classroom Management". Method: The number of postings by the pre-service teacher on the different processes of ill-structured problem solving and the interactions amongst the participants are analyzed. Result: The study reveals the weakness of the pre-service teachers in articulating the problem space and their tendency to go straight to generating solutions without going through the other processes of ill-structured problem solving. This paper further points out that these weaknesses are due to insufficient reflective thinking on the part of the pre-service teachers. Conclusion: Possible strategies to improve the extent of ill-structured problem solving include using films and journal writing to trigger reflective thinking in the pre-service teachers and encourage them to go through the seven steps of the ill-structured problem solving processes. This understanding can inform future use of using asynchronous online discussions to engage learners in ill-structured problem solving. (Contains 3 tables.)