This paper reports the findings of a study that investigated the effect of giving and receiving marginal L1 glosses on L2 vocabulary learning. To that end, forty nine Iranian learners of English were assigned to three different experimental conditions including marginal L1 glosses Giver (n = 17), marginal L1 glosses Receiver (n = 17), and no glosses Control group (n = 15) with a pretest, immediate, and delayed posttests design. The scores obtained from the fill-in-the-blank and translation test confirmed the homogeneity of the three participating groups in the pretest. During three treatment sessions, participants in the giver group were required to perform the three reading comprehension tasks and consult the bilingual dictionary to look up the targeted lexical items, which were highlighted, and write down their L1 equivalents in the spaces given. The participants in the receiver group were asked to carry out the same reading comprehension tasks which included L1 equivalents of the targeted words. The participants in no marginal glosses group took the same procedure while they had no access to marginal glosses. Two days and four weeks after treatment sessions, all participants took the posttests using the same testing package applied in the pretest. Results of one-way ANOVAs revealed that both the giver and receiver group had an influence on L2 vocabulary learning, the giver group made the most favorable progress over time.