The study was undertaken primarily to assess the difficulty level of textbooks used by Secondary 1 pupils in Singapore using cloze readability tests. 174 Express and 192 Normal stream Secondary 1 pupils were first administered cloze tests. One week later, they were administered multiple choice tests in the same content subject: English, Mathematics, History, or Science. The results showed that: (1) Express pupils find their Mathematics and Science textbooks too difficult while Normal pupils find their English, Mathematics, History, and Science textbooks too difficult; (2) as predicted, English speakers obtained significantly higher mean cloze scores than Mandarin or Dialect speakers; (3) although most pupils obtained significantly higher mean cloze scores on the familiar than on the unfamiliar passages, their low mean scores on both types indicate that the majority still find the language of the text difficult to cope with; (4) the criterion of 44% on the cloze was found to be approximately equivalent to the conventional criterion of 75% correct on multiple choice tests, lending more weight to the validity of the cloze procedure as a testing measure in assessing the readability of textbooks in both first and second languages.