Abstract. Aside of day-to-day business in some organizations Enterprise Architecture (EA) seems to be successful while it is not in others that also have notations, models, methods, and even dedicated EA tools. In order to understand these differences we have analyzed the development of EA in six companies over the last eight years. Our analyses showed, that apart from formal structure and processes (i) training and education of architects and non-architects, (ii) improving architects' communication skills, (iii) intensifying EA representation in projects, and (iv) tool support (not replacements with tools), significantly contribute to long term EA success.