This monograph examines controversial issues in theories of morphology and lexical processing in Arabic, a less studied Semitic language with unique phonological, morphological, and orthographic features. After introducing the relevant theoretical debates regarding Semitic morphology and theories of lexical processing as well as the related research evidence, the following research questions are explored through a series of on- and off-line experiments: (i) Are complex words decomposed or accessed as whole units in visual word recognition? (ii) Which morphological units, if any, are relevant in visual lexical processing in Arabic? (iii) Do form and meaning interact to facilitate word recognition? (iv) Are vowels and consonants perceived similarly in word recognition? The results are discussed in relation to Semitic theories of morphology and theories of lexical processing. This work is, therefore, important not only for the study of Semitic morphology and reading in Arabic, but also for understanding lexical representation and lexical processing in general.