Lack of lexical knowledge has been identified as the primary source of reading difficulty. Therefore many theories have been put forward on how to overcome this problem. This‘ paper used Krashen’s theory of vocabulary expansion through reading as a basis for investigating whether reading is the most productive method of vocabulary expansion, by administering
questionnaire to teachers of secondary and tertiary levels of education. The results showed that ninety-six percent (96%) of the respondents agreed with the theory, while four percent (4%) felt that the method of memorizing and learning a new word everyday is better. A number of suggestions on how to expand vocabulary were given.