Today, it is not uncommon to find a project that is run by a team consisting of members from different departments. The success of these multi-functional projects are often dependent on the amount of support the members of the team receive from their ‘home’ departments. This support often is not mandatory, nor under the authority of the management of the project. Leading and Influence without authority therefore becomes a critical skillset to achieve a positive project outcome. By exploring the principles of influence and understanding how they work, leaders of these large-scope teams can build better working relationships, gain more influencing power and use different resources and techniques to persuade and lead others.