I find that many students, not just ESL students, need to work on vocabulary. Sometimes a reading comprehension problem is actually poor knowledge of the vocabulary used, even words we’d expect the student to know. When you ask students comprehension questions, also pick out several words and ask them give you the meaning. If you find they often don't have a clear understanding of the words you choose, then work on vocabulary before you work on comprehension, preferably before they read the passage. "Children’s books have more rare words for each 1000 words than educated adult speech!" For more information about teaching vocabulary, go to: http://21stcenturyhiteachers.wikispaces.com/Vocabulary and at the top of the page, click on "Partial Vocabulary Workshop". There are also links to a number of good websites on the same wiki.