Abstract: A method and system of constraint-based project scheduling. The method comprises maintaining a first database containing project scheduling data associated with at least a current period and a next period of an assignment plan; maintaining a second database containing data associated with a look ahead plan, the look ahead plan covering at least an overlap portion of the next period of the assignment plan such that the look ahead plan overlaps the assignment plan; transferring data associated with one or more shielded tasks having a starting time within the overlap portion of the next period from the second database into the first database as a modification of the project scheduling data associated with the next period of the assignment plan; and executing the project according to the next period of the assignment plan based on the modified project scheduling data associated with the next period in the first database.