Abstract: The present paper studies through experiments the effects of double- glossing, single-glossing, and no-glossing on incidental acquisition and maintenance of new words while reading an English article. The results show that: 1) double-glossing conduces most to incidental vocabulary acquisition, single-glossing plays a significant role, too; 2) double-glossing conduces more than no-glossing to the maintenance of new words, but as for the comparison between double-glossing and single-glossing, single-glossing and no-glossing, the former has no significant advantage.