This study examines the readability of text books used by Year 11 students at a Secondary College in the A.C.T. Twenty-seven texts are examined with the majority being taken from the area of Social Science. The texts are examined using the following measures, The Fry Readability Index, The SMOG Formula, The Cloze Measure, The number of Words per T-Unit and the level of Abstraction of the text. According to these indices between 60% and 84% of the texts are too difficult for students commencing Year 11. This study also examined the interrelationship between the indices. A feature of this study is that it introduces into readability measures a consideration of the number of words per T-Unit and level of Abstraction