In the period 1935-1940, the Iranian Language Academy (Farhangestān) proposed over 1,600 indigenous terms to replace words of Arabic or European origin. Seventy years later, an assessment of the effects or “success” of this activity may be attempted. The Farhangestān’s success cannot be measured easily, by counting the successful words. A study of it requires a strict definition of the term “success” and a detailed analysis of the origin, semantics, usage, stylistics, etc. of each word. The analysis proposed here, using sixty terms, yields a scale of increasing success along which the coined terms may be arranged. The article aims to show that any exact numbers indicating the Farhangestān’s word-replacing success are of limited value; and that it is more interesting to ask how the new terms have been established and how they have systematically changed, and often enriched, the vocabulary of Persian.