Most agile projects rely heavily on good collaboration with the customer in order to achieve project goals and avoid overruns. However, the role of the customer in software projects is not fully understood. Often, successful projects are attributed to developer competence, while unsuccessful projects are attributed to customer incompetence. A study was conducted on eighteen of the latest projects of a software contractor. Quantitative project data was collected, and project managers interviewed, on several issues related to estimates, key project properties, and project outcome. It was found that in projects where collaboration was facilitated by daily communication between the contractor and the customer, they experienced a lesser magnitude of effort overruns. In addition, employing a contract that facilitates risk-sharing may also have a positive impact.