A method and system for selection of a task in proportion to a desired distribution. Specifically, in one embodiment, the present invention discloses a method and system for selecting a task associated with a visiting customer to a web site over a communication network. The customer is assigned to a segment of a target customer base that most closely resembles the customer's characteristics. A plurality of tasks is associated with the segment and can be expressed as a distribution of tasks performed. A current distribution of tasks is determined. The task which provides a new distribution that is closest to a desired distribution of the plurality of tasks is selected to be performed. In one embodiment, the task to be performed is the offering of an advertising promotion to the customer over the communication network.