This thesis examines linguistic similarities and differences between the Russian and Ukrainian languages regarding the word formation of adjectives referring to place names (toponyms). Using contrastive analysis for analyzing the database composed of approximately 1500 shared toponyms, information is presented revealing the use of appropriate derivational paradigms. Tables are provided illustrating important characteristics of toponym stem-endings and the acquisition of their corresponding suffixes. This information culminates in a better understanding of the proper use within each language for the 25 Russian and 18 Ukrainian suffixes used in the derivational models, and its application within language. Analyzing derivational paradigms of these two investigated languages, I found 15 similar and 7 different models resulting from the word formation process. This information brings a clearer picture for both languages on how derivational paradigms are used in the proper formation of adjectives.