This paper discusses Alija Isakovic's commitment and contributions to the processes of reaffirmation Bosnian language within Serbo-Croatian linguistic unitarism in the second half of the 20th century. We have shown the historical context of the language policy and Isakovic's significant work for the selected theme. The focus of this paper is on the sociolinguistic text "Varijante na popravnom ispitu" and the lexicographic work Rječnik karakteristične leksike u bosanskome jeziku, which represents a kind of struggle for the specificity of the Bosnian variant and characteristic lexicon of Bosnian language in that linguistic norm. The results of Isakovic's work are noticeable in the Yugoslav period (partial change in the field of official language policy), but it's also noticeable in period of state independence when language policy was created based on Isaković's concepts.