This study, situated in an EFL context, aimed at discovering the ways purposes behind reading activities influence vocabulary knowledge gain and retrieval. Seventy five elementary learners of English were randomly assigned to three groups of âfree readingâ, âreading comprehensionâ and âreading to summarizeâ. A modified text was administered to all the three groups. The data in both immediate and delayed post-test revealed that both vocabulary learning and retention were greatly influenced by the purposeful reading activity. The Scheffe post-hoc test revealed that the mean scores of the âsummarizingâ and âreading comprehensionâ groups were significantly different from the mean score of the âfree readingâ group. But the results did not indicate any significant differences between the mean scores of the two groups of âsummarizingâ and âreading comprehensionâ. However the strength of association for the immediate post-test and the delayed one showed that a large part of the variance between the three groups could be explained by the reading purpose.