Lexical Functional Grammar (LFG), which was introduced by Joan Bresnan and Ronald Kaplan at the end of 1970’s, is a reaction to transformational grammar. I intend to use LFG for analyzing the grammatical errors of Turkish adults, who were learning Italian as a foreign language. For finding out these errors, I distributed a grammaticality judgment test of 30 questions to 20 Turkish students, 10 of whom were learning Italian at the intermediate level, and 10 of whom at the elementary level. I made a statistical Chi-Square analysis for identifying in which parts of the Italian sentences and phrases coordinated with ‘ma’ (but), ‘o’ (or), ‘e’ (and), ‘né… né’ (neither…nor), and ‘non solo... ma anche’ (not only...but also) errors occurred. I aim to show that LFG proves the existence of cognitive and linguistic processes in the human mind.