Over the years software quality is becoming more and more important in software engineering. Like in other engineering disciplines where quality is already a commodity, software engineering is moving into these stages. The Team Software Process (TSP) was created by the Software Engineering Institute (SEI) with the main objective of helping software engineers and teams to ensure high-quality software products and improve process management in the organization. This paper presents a methodology for assessing an organization against the TSP practices so that it is possible to assess the future gains and needs an organization will have during and after the implementation of TSP. The gap analysis methodology has two pillars in terms of data collection: interviews and documentation analysis. Questionnaires have been developed to guide the assessment team on the task of conducting interviews and further guidance has been developed in what and where to look for information in an organization. A model for the rating has also been developed based on the knowledge and experience of working in several organizations on software quality. A report template was also created for documenting the analysis conclusions. The methodology developed was successfully applied in one well known Portuguese organization with the support and validation of SEI, and several refinements were introduced based on the lessons learnt. It is based on the most know reference models and standards for software process assessment – Capability Maturity Model Integration (CMMI) and ISO/IEC 15504. The objective of this methodology is to be fast and inexpensive when compared with those models and standards or with the SEI TSP assessment pilot.