Vocabulary knowledge has been found to have a strong effect on reading comprehension. The components of vocabulary knowledge include breadth (the number of words a learner knows) and depth (the amount of knowledge a learner has about a specific word).

• Breadth of vocabulary knowledge is important to English language learners, as they frequently know far fewer English words than native speakers and find themselves at a disadvantage, particularly in academic contexts (Folse, 2004; Qian, 1999).
• Depth of word knowledge includes knowing how to pronounce and spell the word; what the root of the word is, whether there are prefixes or suffixes attached to the word, and what part of speech the word is; how the word is used in sentences; what connotations the word has; whether there are multiple meanings of the word; and in what contexts the word is used.

For example, deep knowledge of the word rider means knowing how to spell the word, knowing that the "i" is pronounced /ay/, knowing that the word is a person or thing (a noun), knowing that because the word has the suffix "er" it refers to a person or thing that rides, and knowing that the word might appear in a sentence such as "There was no rider on the horse." Deeper knowledge of the word means knowing that rider has other meanings, and that another fairly common use of the word is to refer to an additional clause or piece of legislation that is attached to another bill without being related to the original piece of legislation. Still deeper knowledge of the word would mean knowing that in this case, the connotation of the word may be somewhat negative, as can be seen in the sentence "The senator was famous for adding riders that were unrelated to the bills to which they were attached, but which would bring industry and money to his state."

Syntactic processing involves understanding the structures of the language and making connections among words in a sentence or sentences in a text. For example, learners need to learn the forms that signal different word meanings (e.g., -ed form of verbs to denote past tense and passive voice), forms that change word meanings (e.g., prefixes such as non, in, im, and un that make words negative, and words that bring cohesion to a text (e.g., however, therefore, nevertheless).

Background knowledge facilitates reading comprehension. Readers generally understand texts more easily if they are familiar with the topics covered and the genres and text structures involved. Especially for beginning- level readers, readings about culturally familiar topics should be selected, and teachers should build on ideas and concepts from learners' cultures and personal experiences whenever possible. For example, prior to reading about schooling in the United States, the teacher might ask learners about schooling in their home countries, what ages children go to school, how classes are divided, and what kind of testing or assessment is used. The teacher might then move to a discussion of what the students know about schooling in the United States, asking similar questions. Important vocabulary words (especially those in the reading) such as grades, assessment, testing, classes, can be written on the board as they come up during the pre-reading discussion.