The article aims to review and evaluate research reports—mainly publications in English—on businesses referred to as early internationalizing firms, with a special focus on terminology used by various authors with regard to such firms. Duliniec critically reviews several dozen research papers that have been published in this area over the past two decades with the view of identifying the most common terms and definitions of early internationalizing firms. The process of early and quick internationalization of companies has been increasingly observed in the modern world, according to the author, and its importance in explaining the mechanisms of the firms’ internationalization has been growing. Early internationalizing firms are an important field of research on the internationalization of companies in many countries. In Poland, research in this area has been scarce so far, Duliniec says. The analysis conducted by the author shows that terminology used in the field is far from uniform, while the definitions and research conclusions are highly diversified. Three terms are most often used in research reports with regard to the analyzed type of companies: new international ventures, born globals, and early internationalizing firms, the author notes. Early internationalizing firms are the widest term used in this case, Duliniec says, bringing together the views of various authors.