In 2009, the Federal Republic of Germany signed the United Nations Convention on the Rights of Persons with Disabilities. Since then, schools in all federal states have been called upon to evolve into inclusive schools. This paper presents the Index for Inclusion as a tool for planning and evaluating school development, using the example of the Protestant Heinrich-Albertz Primary School. In addition to a brief description of this school and a clarification of the term inclusion, the focus is on describing the Index for Inclusion, which was developed in the UK and has been available in Germany since 2003, and documenting its practical implementation within the framework of school development. Furthermore, essential features and methods of successful school development are identified, and finally, the possibilities and limitations of the Index are highlighted in a conclusion.