From an historical perspective, it can be said that there are two basic models for the creation of CI units: the constructed and the evolutionary. In the constructed model, the CI unit owes its existence to the decision of one person (or, at most, a handful). Someone says, "Let it happen," and it does. At that point, the CI unit must begin to operate and justify the decision to create it. In the evolutionary model, the CI unit owes its existence to a perceived need by the firm, or a part of the firm, for its services. It gradually comes into existence to meet a particular need, and then must seek out additional tasks and missions to justify its continued existence.

The way in which each particular unit was established will tend to influence its growth, manner of operation, and ultimate survival, as suggested by the following two lists.