Contrastive analysis is vitally associated with foreign language teaching. A competent bilingual's intuition about the relationship of the forms in the two languages is the most important part of the valid data for analysis. By means of contrastive analysis major grammatical problems for American students learning Modern Standard Arabic (MSA) noun modifiers have been predicted. It has been found that patterns in the two languages are very easy if they have similar forms, meanings, and distributions. Grammatical categories that are absent or missing in the foreign language, but present in the learner's language, may constitute an easy pattern. If one obligatory pattern in the foreign language is set against more than one optional pattern in the learner's language, we have the case of a merged category. The equation of one obligatory pattern in the learner's language to more than one in the foreign language is a split category. The learner has one familiar significant pattern which could be equated to two (or more) significant or nonsignificant patterns in the foreign language. For the nonsignificant ones the alternate forms do not contrast but are in complementary distribution. (Author)