The Study aimed at determining the availability of critical thinking skills in the activities of the book of the Arabic language (Almu'ns) in grade 12, and the different percentage of the availability of such skills in the activities with different skills. To achieve this, the researcher prepared a list of (31) critical thinking skills, which should contribute to the activities of the book. They are divided into (5) key skills (identification, inference, balancing, interpretation and evaluation). The study had analyzed all (772) activities contained in the book and .. found that the numbers of the critical thinking activities in the book are. (395) activities which represent 51% of the total activities. Those. . activities were divided into the five key skills to varying degrees. The interpretation skills got (41.2%), inference skills (25%), identification skills (17.9%), evaluation skills (11.6%) and balancing skills (4%( At the level of sub-skills, the numbers of skills which are taught in the activities in the book are (26) skills, which represent (83.8%) of the total skills of the instrument. There are no activities in the book that develop the five skills of the critical thinking skills, namely, (distinguishing between opinions and facts, citing stanzas from different poems that are similar in meaning to the stanzas in the book, identifying the similarities between the various issues presented in the text, differentiating between two terms in the text, and identifying errors in the text In light of the results and its discussion, the study provided a number of recommendations including: reviewing of Subject Scope & Sequence, inclusion of critical thinking skills in the curricula of the Arabic language in a systematic and clear approach, allocating enough space in teacher preparation programs in colleges of education to the critical thinking skills and its different forms, and methods of teaching