Small and medium-sized enterprises (SMEs) make up the most important sector of a nation's economy. They provide employment opportunities for millions of individuals; their work is strongly costumer-oriented; they are a source of innovation and entrepreneurial spirit; they serve as sub-contractors for large corporations, and they create competition and are the seed for enterprises of the future. Various countries, because of basic differences like area surface, population, per capita income, industrial development level, etc., have employed various strategies directed to SMEs development. On the other hand, some countries like due to high population and unemployment rates, have directed SMEs development to solving unemployment problem. This research aims to review policies in relation to SMEs at a global level. The status of SMEs according to key characteristics investigated. Summarily, SMEs in Iran as a case is discussed. Finally based on the review, findings and lessons, conclusion will be drawn, and guidelines for policy formulation will be suggested.