This book is a comparative study of Argument Structure (AS) of Verbal Derivations in English and Persian. It shows how the morphological processe of derivation can affect the argument structure of the verb base. To study such an effect and to compare the simillar nature of AS in the two languages, we drew Lexical Conceptual Structure (LCS) of both stems and derived words. The LCS of each derived word illustrates the fact that most changes in AS of a word are the result of what happens to the semantic primitives of its LCS.