The portfolio is a widespread tool for formative assessment. There are many publications in support of this claim. Less literature describes the capabilities of the portfolio as a tool for self-assessment, in particular for self-evaluation of the school as an institution. This is a reason to consider the chances of the portfolio as a technology for self-assessment that provides useful information and liaise between performance measurement and quality, and facilitates motivation of teachers and leaders to achieve the objectives and results, and school development. The article analyzes the legislation in the Republic of Bulgaria, which regulates the development and implementation of portfolio in education and the educational process. In theoretical aspect explore the benefits that portfolio provided as an integrative model for self-assessment in the Bulgarian school in two contexts: students and teachers who carry out individual self-assessment and self-evaluation of the school as an institution. There are recommendations for monitoring, analysis and evaluation of the standards achieved in school institutions using portfolio in order to improve the quality of education.