Adverbs and adjectives have always been in the center of attention among different linguists. They have been putting various questions relating to the usage of these two parts of speech and trying to find answers to them. Adverbs and adjectives are used as complements in a sentence and give some sense to other parts of speech. Therefore, I felt the necessity to consider these parts of speech more deeply and compare them since they have many common grounds, whether similarities or differences. The practical value of this book is that it can serve as a manual for the learners of English grammar, can help distinguish adverbs from adjectives and escape some confusing cases in their usage among non-native speakers of the English Language.