Intentional Interim Ministry (IIM) was initiated by the U.S. Presbyterians after they noticed that long settlements of ministers were usually followed by short ones, due to problems arising between the new ministers and the congregations. Why? Often it stemmed from what, on the surface, were unrealistic expectations by the congregation; however, this was a symptom of deeper issues, and it appeared that a specialised ministry was needed to assist the transition from one minister to the next.
Of course, it was soon realised that there were other kinds of transitions that needed attention as well, e.g. changing roles of the minister, new partnerships, a changing demographic, spiritual changes in society, history of conflict, betrayal of trust, death, trauma or long-term debilitating illness of a minister, or the transition to no longer having a minister.
In these situations there is a major change, which can happen intentionally or not, which then necessitates a transition to a new state. Change always brings grief over the loss of a past, which must be dealt with, but also hope in anticipation of the new. The work of the congregation required to move from old to new can be assisted by good leadership; hence, the birth of IIM.