Competitiveness is a concern for all economic agents and even for an entire society due to its relationship with economic development, increased production, and employment. The paper offers an overview of the main theories from the comparative advantage to the theories of competitive advantage and the new theories of competitiveness and international trade. The qualitative/ quantitative method was used with a documentary analysis technique from secondary sources of information. It concludes that constant returns and perfect competition determine competitiveness in traditional theories, whereas increasing returns and imperfect competition characterize competitiveness in the new approaches.