Robert Lado (1957), as well as most contrastive linguists, have shown that the learner's first language may have a big role to play in the process of second language learning. Due to differences between languages, whether in their syntactic, grammatical, pragmatic, or phonological systems, difficulties in learning a second language may arise. One of the most frequent difficulties Arabic L1 students face when learning the English language is learning the English language grammatical system and their ability to communicate effectively according to that. This paper pinpoints common grammatical mistakes which English learners make and possible solutions to such mistakes are listed and explained. Illustrations are given of how the differences between the Arabic and English language regarding the grammatical system cause L1 Arabic learners of English to make mistakes and errors in their English learning process and how this prevents learners from meaningful English communication. The aim of this paper is to prove that English students make similar grammatical and syntactic mistakes which are repeated and frequent. That is, many grammatical mistakes of Arabic native language speakers are orderly made and regular. Errors in the English language grammar and syntax which students commit are not random and are found to be very much due learners' mother-tongue interference. Arabic first language interference is found to play an important role in English second/foreign language especially when it comes to learning the English grammatical and syntactic system. For instance, due to the Available online differences between Arabic and English in terms of the use of determiners, prepositions, conjunctions, using singular/plural forms and proper word order many problems arise. English learners from an Arabic mother-tongue can be negatively affected by transferring from their parent or first language. This paper concludes a number of these negative interference problems, discusses them thoroughly and lists a number of possible solutions which are seen to be effective in English teaching classrooms and environments.