We demonstrate that the use of Performance Frameworks for the procurement of construction projects by public sector organizations in the UK (specifically, in England) leads to significantly improved outcomes in terms of time, cost, quality, sustainability and closer relationships, than the traditional ‘open tender’ approach of procuring discrete projects, individually. We identify the factors that lead to such improvements. We label these: supplier’s task performance factors (project staff, execution approach, competence of firm and structure of firm); supplier’s contextual performance factors (trust and collaboration, culture and conscious behaviour); and client’s organisational factors (incentives, performance monitoring, procurement approach and communication). And we offer a performance improvement model that will help project managers to select the most appropriate suppliers at the procurement phase, to achieve successful project outcomes. The model can also be used to drive project performance further, by adopting client’s organisational factors during the procurement and construction phases. By applying the research conclusions, suppliers will be able to focus on communicating their strengths in the relevant aspects of task and contextual performance for technical tender proposals, and so increase the value of their services and the probabilities of winning work. And the analysis can be used by policy makers to help in drafting regulations and legislation on formal frameworks, in ways that will improve the delivery of policy objectives.