Projects have crucial importance in the business world as they contribute daily in adding value to all sorts of products and services. Projects have become the usual way of producing new products and adding value to the existing ones. They are also used to make progress in organizations and as a tool to win more of market share. Project management is a management discipline that studies and represents ways of managing projects, and project teams. Project teams are a necessity in achieving today's businesses and a part of modern organizations responsible for progress and execution of project work. The main goal of this graduate paper is to show the development of project teams and their credibility in the realization and success of the projects. Project teams represent the very core of project business, today's progress and modern business prosperity. They are cornerstones od all activities geared towards projects and are bearers of social and technological global development. The human factor is crucial for every business and therefore project. Because of that, through the initial emphasis of the role of a project manager and many of his responsibilities, the importance of successful project team leadership is highlighted while the part with team development phases provides guidance for current and future project managers to create a successful project team. Interpersonal relationships are emphasized through communication and psychological profiles of people working together in team. Also, there are specified stages of team development with detailed breakdown of each phase in the relations within the project team. Positive and negative aspects of each phase of development are presented. At the same time, the importance of handling barriers of team development and solving conflict situations is highlited. Key features of succesful project teams are highlighted. The key part of the work is secondary research that demonstrates the need for different approaches to project teams and their exceptional importance for the project's ultimate success.