This research investigated the effect of three definitional, sentential, and textual vocabulary learning strategies on Iranian intermediate EFL learners' vocabulary learning and retention. Based on Oxford Solutions Placement Test, of 94 total population, 66 Iranian EFL learners were selected as homogeneous participants at the intermediate level from a private English Language Institute in Rasht, Iran. Next, according to the quasi-experimental design, characterized by administration of a pretest, treatment, and a posttest and a delayed posttest, the learners were randomly assigned to two experimental groups of textual (TG), sentential (SG), and one control group of definitional, (DG) each with 22 participants. A familiarity test of vocabulary was administered to certify the learners' familiarity with the targeted vocabulary items. The groups were pretested on their current knowledge of vocabulary, after which they received a 20-session text-based, sentence-based, and definition-based instructions of vocabulary. In addition, all groups attended the posttest of vocabulary at the end of the treatment sessions. The results of the immediate and delayed posttests analyzed using one-way ANOVA revealed statistically significant differences in the performances of the three groups in favor of TG group that gained and retained higher rates of vocabulary items than did the SG and DG groups although the SG group was more successful. Further findings and implications are discussed in the paper. The findings of the research can be utilized by the teachers, materials developers, and education authorities to provide textual-based vocabulary instruction for Iranian EFL learners.