This paper reports the process of informal learning in the pre-consulting phase in management-consulting firms in Indonesia. As the consulting industry significantly grows in Indonesia, more organisations use consultant services to improve their business. Pre-consulting is an important phase to define the right solutions, which involves a lot of informal learning activities. More, team diversity and client's uncertainty also influence this phase and lead to team conflict and impact to team performance. After developing a conceptual exploration based on several key constructs and their interrelationship, this paper uses empirical examples of actual consulting firms to study. A qualitative study of observation and semi in-depth interviews to six informants representing four medium size-consulting firms in Jakarta were done. This paper suggests that a team can create innovative solutions to the prospective clients and get the project if they can learn informally and manage the conflict caused by team diversity and client uncertainty.