When the duration of project tasks is uncertain, the timing of the availability of resources, such as materials, equipment, in-house crews and subcontractors, can be one way to expedite projects. ANN van ACKERE shows how the availability of resources can affect project duration, and explains how inadequate accounting for costs can lead to conflicts and suboptimal project planning. She concludes that cost estimates, lead-time and resource planning are interrelated and should be analysed jointly.