Achieving good scalability from parallel codes is becoming increasingly difficult due to the hardware becoming more and more complex. Performance tools help developers but their use is sometimes complicated and very iterative. In this paper we propose a simple methodology for assessing the scalability and for detecting performance problems in an OpenMP application. This methodology is implemented in a performance analysis tool named ScalOMP that relies on the capabilities of OMPT for analyzing OpenMP applications. ScalOMP reports the code regions with scalability issues and suggests optimization strategies for those issues. The evaluation shows that ScalOMP incurs low overhead and that its suggestions lead to significant performance improvement of several OpenMP applications