This paper is divided into two parts. The first part is about the development and periodisation of the Croatian language throughout history. We have described the journey of Croatian language through it is making, affirmation to different politics through centuries, and lastly the confirmation as the official language oft the Republic of Croatia. In the second part, we tried to answer one of the burning questions that is often asked among the linguistic circles on the territory oft the former Yugoslavia, and among the general public, and that is whether Croatian and Serbian are one or two languages. We have studied both sides of the argument intesively and tried to understand the evidence that support them. It is a question that interests not only Croatian and Serbian linguists, but a number of foreign Slavists as well. This interest is surely sparked by other, non-language based facts as well, and they surely had an influence on the formation of Croatian standard language on one side, and Serbian standard language on the other.