The purpose of the study was to investigate the readability of grade 7rnbiology textbook of Addis Ababa region. The sources of data were grade 7-rnbiology textbook, grade 7 biology teachers, and students. Four datarncollection instruments were used: teachers' questionnaire, students'rninterview guide, two different comprehension tests, and readabilityrnassessment checklists. Accordingly, 20 teachers were made to fill thernquestionnaire, 50 students were interviewed, two different groups of twornhundred students took two types of comprehension tests, and readabilityrnassessment checklists, which consist of 52 guide items, were used. Thernmethod used to investigate the study was readability assessment based onrnsurvey and selection of unit of analysis. Both quantitative and qualitativernmethods were used.rnThe result of the study revealed that the grade level estimate of therntextbook is grade 10, which is beyond the students' grade level. The readingrnage of the text and students' average age is almost the same. However, byrnconsidering the average age of the students of the sample schools, it wasrnfound out that the students' age and grade level is inconsistent.rnFrom the result of comprehension tests, it was found that readingrncomprehension depends on the readability levels of the passages of therntextbook.rnAn investigation was also made regarding the legibility of the text. Itrnwas obtained that inappropriate labels, poor lettering conditions, small sizernof letters, long length of lines (statements), narrow margin space, less weightrnrnrnrnrnrnrnof print, unsuitable reading conditions and unclear and not well visiblerndiagrams were some legibility problems.rnThe main readability problems of the text were found to be: absencernof glossary, availability of unfamiliar words in most parts of the units,rnabsence of color or bold signs for new and unfamiliar words, students lessrninterest and motivation to compute exercises and practical activities,rninadequate periods allotment, inappropriateness of the content to thernmaturity level of the students, students inability of reading the text with thernintention of understanding and remembering, availability of long sentencesrnin most units of the text, and teachers unawareness of readability factors.rnRegarding adequacy, simplicity and clarity of illustrations it wasrninvestigated that: examples are very few, exercises and activities are notrnadequate, some experiment activities lack clarity and simplicity, in somerntopics and subtopics; tables, charts, diagrams and pictures lack clarity andrnsimplicity and some of them are not self-explanatory.rnIt was also examined that the sequence and integration of contents, therncolor of ink, appropriate size of spaces between paragraphs and lines,rnavailability of chapter summaries and review questions, the relationship ofrncontents and illustration, the relevance of contents to the daily life ofrnstudents, appropriateness of the brightness ratio between the book and thernsurrounding table, the presence of related reading materials in each topic andrnsubtopic, variety and quality of exercises and relevance of ideas, coveragernand values were obtained to be satisfactory.rnThus, curriculum developers and other pertinent bodies should see tornit that the textbook should be revised to be readable by considering thernabove-mentioned readability factors