The present invention measures reading fluency, which is simultaneous decoding and comprehension. Whether or not a person is a fluent reader is determined by the size of the visual unit, or sting of letters, used in word recognition. In order to measure the size of the visual unit used in word recognition, a lexical decision task (“LDT”) is used in which short and long words are presented on a display device. The person determines if the string of letters formulates a word. The person enters their response on an input device and the results are recorded. A score is calculated that measures reading fluency. The ability to correctly identify a string of letters as a word using holistic processing, rather than letter-by-letter, is the hallmark of a fluent person.