The current study examined individual differences in the effects of retrieval from long-term memory (i.e., the testing effect). The effects of retrieving from memory make tested information more accessible for future retrieval attempts. Despite the broad applied ramifications of such a potent memorization technique there is a paucity of research tailored toward scrutinizing variability in the effect. Multiple measures of working memory capacity, attention control, episodic memory, and general-fluid intelligence were collected in addition to performance in a standard paired-associate testing task. A testing effect was observed and there was a great deal of individual variability in the magnitude of the effect. This variability was best accounted for by memory and intelligence constructs. Furthermore, the pattern of results is consistent with the notion that students with poor memory abilities and lower general-fluid intelligence benefit more so from testing memory than high ability students. (Contains 2 figures and 4 tables.)