Software engineering is the computer science discipline concerned with developing computer software. However, software engineering does not only include the technical perspective of producing software. It also involves management issues, such as planning, controlling, and monitoring a software project. A project typically embraces a structured set of activities, which are performed in a pre-determined sequence. The initial activity is generally the process of planning the project, which according to some is one of the most important and crucial efforts in order to achieve pre-defined objectives. Other states the opposite and claim that too much planning may obstruct development creativity. Current thesis explores the planning paradigm and the significance of planning efforts in the Swedish software industry. Contemporary literatures on software project planning are reviewed and presented. Moreover, the result of an empirical study, examining the relationship between project planning and project success, is presented.