In general, incidental vocabulary acquisition is represented as the "picking up" of new vocabularies when students are engaged in a variety of reading, listening, speaking, or writing activities. Research has shown when learners read extensively incidental vocabulary acquisition happens. Many EFL students cannot be involved in reading activities in Iran. For involving students with more reading activities in EFL classroom teaching and likening the results to the vocabulary exercises, the researcher directed a research for about five weeks in an EFL class. The subjects were 120 male and female students at high school level. Half of them (RP group) read chosen passages after which they did different vocabulary activities and exercises. The other half (RO group) received the reading only (RO) treatment, i.e., they only read several reading texts. The significance of the present study lies in the fact that it was able to compare the effectiveness of reading only and reading plus vocabulary enhancement activities on types of immediate and delayed lexical word recall in a single study. The researcher employed the Vocabulary Knowledge Scale to measure students' knowledge of 60 vocabulary items. The results showed that RP group gained better results than RO group on both acquisition and retention tests. This indicates that "Reading plus" method is more effective in increasing knowledge of vocabulary and long term retention in male and female EFL learners in Iran.