The present study was designed to investigate empirically the effect of Vocabulary Self-Selection strategy and Input Enhancement strategy on the vocabulary knowledge of Iranian EFL Learners. After taking a diagnostic pretest, both experimental groups enrolled in two classes. Learners who practiced Vocabulary Self-Selection were allowed to self-select each word from the text they wanted to, but the learners who practiced Input Enhancement strategy one session later than the other group, were just allowed to choose the words among the textually enhanced ones which were just limited to the finalized words of the Vocabulary Self-Selection group. After about three months of treatment, seen and unseen posttests were administered. The results revealed positive effects of both strategies on the vocabulary knowledge of the Iranian EFL learners. Thus it could be safely concluded that Vocabulary Self-Selection and Input Enhancement strategy were quite effective in the development of vocabulary knowledge. The performance of the two groups of Iranian EFL learners on the achievement posttest, as statistically shown, indicates that the Vocabulary Self-Selection group could outperform the Input Enhancement group on the vocabulary knowledge. The results revealed positive effects of both strategies on the vocabulary knowledge of the Iranian EFL learners. It was finally concluded that Vocabulary Self-Selection group outperformed those in Input Enhancement group. Thus it could be concluded that Iranian EFL learners who practiced Vocabulary Self-Selection strategy outperformed those who practiced Input Enhancement. Vocabulary Self-Selection strategy fostered vocabulary learning.