A system and method are described for intelligently sourcing demand forecasts within a supply chain management (“SCM”) system based on a constrained supply chain model, in light of material and resource constraints. For example, a computer implemented method according to one embodiment of the invention comprises: calculating a demand forecast identifying anticipated demand for a product over a specified time period; identifying current sales orders for the product with delivery dates scheduled during the specified time period; generating an open forecast for the product based on the current sales orders and the anticipated demand; and sourcing different percentages of the open forecast from different plants, the percentages selected based on supply chain material and/or resource constraints. In addition, after the demand forecast is sourced, one embodiment of the invention employs additional techniques for intelligently sourcing new sales orders entering the SCM system.