The present study investigates the interaction between two types of explicit instructional approaches, deduction and explicit-induction, and the level of foreign language aptitude in the learning of grammar rules. Results indicate that on the whole the two equally explicit instructional approaches did not differentially affect learning performance. Among the components of language aptitude, memory for text correlated significantly with gain scores. In learners with good textual memory, explicit-induction produced significantly better results in the delayed posttests. Although deduction did not produce significantly better results in the delayed posttests in learners with bad textual memory, these learners tended to perform better under this learning condition. These results suggest that learner characteristics can interact with instructional conditions to affect learning performance and equally explicit instructional approaches can have differential effects on different types of learners. (Contains 4 tables and 4 figures.)