||High opportunities to respond (OTR) have been touted as being a key factor in a popular and effective drill procedure called incremental rehearsal (IR). However, IR has also been criticized because it takes more instructional time than other drill procedures and can be less time efficient. The current study compared the effectiveness and efficiency of a high (44 OTR), medium (27 OTR), and low (14 OTR) OTR version of IR using 23 sixth, seventh, and eighth grade students. Eleven students had low IQ scores (M = 68.18, SD = 6.82) and 12 students had average IQ scores (M = 101.00, SD = 6.63). Students were taught six Esperanto words during each condition. Effectiveness was based on 1- and 3-week retention measures and efficiency was determined by evaluating the number of words initially learned, retained at 1 week, and retained at 3 weeks per minute of instruction. A within-subjects repeated measures ANOVA was used to evaluate both the number of words recalled and the number of words recalled per minute of instruction. Results for both participant groups demonstrated that the high and medium OTR conditions were equally effective. However, students retained the most words per minute of instruction during the medium OTR condition, so this condition was the most time efficient. The number of words retained 1 week after instruction during the high and medium OTR conditions was not significantly different for the two participant groups. However, the number of words retained 3 weeks after instruction during the high and medium OTR conditions was significantly different for the two participant groups, suggesting that students in the low IQ group forgot a significant number of words between the 1- and 3-week retention measures, whereas the average IQ group did not. Limitations and implications for practitioners and future researchers are discussed.