The purpose of this paper is to study theoretical approaches to vocabulary teaching and learning, and to suggest practical instructional methods to maximize EFL learners` vocabulary acquisition. For this purpose the paper firstly reviews the definition of knowing a word from the perspectives of spoken form, letter form, word meaning, grammatical function, and register. Two approaches to vocabulary teaching and learning, respectively, planned/unplanned teaching and intentional/ incidental learning, are investigated based on previous research findings. Factors to influence vocabulary acquisition are frequency, pronunciation, saliency, imageability, contextuality, vocabulary input processing, and vocabulary network. Word lists, mnemonic techniques, word cards, saliency, computer programs, dictionary are suggested to be made use of as practices to aid learners` vocabulary acquisition. The most noteworthy finding from the literature survey is that teaching vocabulary as lexical sets was ineffective since they interfere with lexical inference.