An evaluation of elementary social studies textbooks indicates that eight factors are making textbooks harder to read. These factors are: (1) the reading level of the book and/or the range of reading levels within it; (2) long sentences and/or too many concepts within a sentence or paragraph; (3) the use of vague terms, technical vocabulary, and words that have several definitions; (4) too much content and/or textbook is too long; (5) new concepts in familiar material; (6) new content material which is unfamiliar to the teacher or student, especially content from anthropology, economics, political science, and sociology; (7) the need for materials or activities that are not covered in the textbook; and (8) the use of primary source material. Although there are various factors that make some of the newer textbooks harder to read, reading level is not as much of a problem as it used to be. A comparison of textbooks published before and after 1972 indicates that the average reading level and range of reading levels within the textbooks is decreasing. Results of readability tests for various commercially published texts are included. (Author/DE)