Reading is an indispensable tool for academic success globally and access to good quality of life in the 21st century. As an aspect of English language instruction in Gambian schools, reading is not being properly taught and it is evident that students are losing interest in reading as the culture of reading is gradually fading away from schools. These problems have been identified as some of the factors responsible for the perennial mass failure in English language examinations. Therefore, this study examined the effect of Interactive Read-Aloud and Sustained Silent Reading Instructional Strategies on students’ achievement and interest in reading. Also, the moderating effect of vocabulary knowledge on students’ achievement and attitude was investigated. The study employed a pretest, posttest quasi-experimental design to test three null hypotheses using two treatment groups and a control. Results showed that Interactive Read-Aloud and Sustained Silent Reading had significant main effect on students’ learning outcomes while vocabulary knowledge had no significant effect. Also, there was no interaction effect of treatment and vocabulary knowledge on learning outcomes in reading. Recommendations were made on how to improve the quality of instruction, students’ achievement and interest in English language.