The Project Management Triangle (called also Triple Constraint) is a model of the constraints of project management. It is often used to illustrate that project management success is measured by the project team's ability to manage the project, so that the expected results are produced while managing time and cost.

Like any human undertaking, projects need to be performed and delivered under certain constraints. Traditionally, these constraints have been listed as 'scope,' 'time,' and 'cost'. These are also referred to as the 'Project Management Triangle,' (also known as the 'Iron Triangle') where each side represents a constraint. One side of the triangle cannot be changed without affecting the others. A further refinement of the constraints separates product 'quality' or 'performance' from scope, and turns quality into a fourth constraint.