Enhancement Techniques are conducive to incidental vocabulary learning. This study investigated the effects of two types of enhancement techniques-multiple-choice glosses (MC) and L1 single-gloss (SG) on L2 incidental learning of new words and retention of them. A total of 89 university learners of English as a Foreign Language (EFL) were asked to read the same reading texts with the two types of glossing and no glossing. Vocabulary acquisition was measured with the vocabulary knowledge scale (VKS). The results indicated that there were obvious vocabulary gains for both MC and SG groups. MC glossing is more conducive to incidental vocabulary learning than SG glossing in both immediate and delayed vocabulary post test. What's more, learners with larger vocabulary size demonstrated much more significant gains than those with small ones.