This study is divided into tow main parts . The first part deals with the principles of Grammatical Interpretation in the ancient studies of Arabic . It consists of five chapters. The first one discusses the concept of regularity and irregularity in language study. The second chapters shows the meaning of the term " origin" ( Aşl) and " branch" ( Far' ) in Arabic linguistics . The Third chapter discusses Grammatical Analogy and its types . The fourth one deals , in some details , with the grammatical arguments which comprise the theory of Arabic Grammar . In the fifth chapter the Grammatical Interpretation in the ancient Arabic studies is thoroughly discussed. The second main part of the thesis is dedicated to the study of Grammatical Interpretation in the modern Arabic studies. It consists of three chapters. The first one deals with the grammatical interpretation in the views of twenty Arab linguists. The second chapter discusses their opinions on the external influence on syntactic argumentations in the ancient time . The third chapter shows the standpoints of modern Arab linguists from Grammatical interpretation as discussed in the previous chapters . The conclusion of the thesis puts forth the results of the study, with some suggestions, about the open questions that need more investigation.