Construction process is vulnerable to uncertainties if the constraints at bottlenecks cannot be effectively identified and removed in advance. The present means of look-ahead planning does poorly in locating constraints hidden in the processes, the supply chain, and the information flow. This problem becomes more acute when the project is very complex and project players are distributed over a large scale. With the intention of implementing Lean Construction principles and the Theory of Constraints, a distributed scheduling tool, i.e. Integrated Production Scheduler (IPS), is proposed to improve the reliability of look-ahead plans, reduce uncertainties in supplies, resolve resource conflicts and alleviate delays in processes. The types of constraints modeled in the IPS are specified and a new method for look-ahead planning called Integrated Constraints Modeling is introduced. By presenting a three-layered structural model, the IPS planning process is addressed in details and the role of distributed systems is also discussed. The full implementation of IPS is based on the Internet technology, especially Java and XML.