The work is devoted to research in the development of the small- and average-size enterprises in Bulgaria from the beginning of the 20th century up to now. A starting point of the author is an attempt to give a definition of a small enterprise possessing a certain specific profile in comparison to large firms. Modular classification of small- and average-size enterprises is presented. A brief comparative analysis of small- and average-size enterprises in the European Union and Bulgaria has been performed and is presented.