Most adult English Language Learners (ELLs) in the United States struggle with the basics of English literacy and reading comprehension. The lack of metacognitive awareness during reading prevents ELL students from engaging actively in the learning process. The CALLA method was used as a conceptual framework for explicit instruction. The problem is that approximately 65% of ELLs who are enrolled in the beginning course in the ESL program at El Paso Community College (EPCC) in Texas struggle to pass the reading exit exam required at the end of each semester. The purpose of this quantitative comparative study was to examine the effects of explicit instruction of vocabulary building and metacognitive strategies on L1/L2, L2 only groups, and traditional instruction on a Control group for reading comprehension of adult ESL students at EPCC. After data analysis, only 30 students' scores were used. There were two treatment groups and a control group. One treatment group (n = 9) received explicit instruction in L1 and L2 together. The second treatment group (n = 6) received explicit instruction in L2 only. The control group (n = 15) received traditional instruction. A mixed repeated measures ANOVA was conducted to assess the difference between explicit instruction of vocabulary and metacognitive strategies as an intervention and traditional instruction on participants' scores on reading comprehension across two-time levels (pretest, posttest). No significant difference existed for time (pretest, posttest) within treatment groups (L1/L2, L2 only, Control) for reading comprehension scores of ESL students. No significant difference existed between treatment groups (L1/L2, L2 only, Control) within levels of time (pretest, posttest) for reading comprehension scores of ESL students. The results were statistically non-significant for between groups and within groups. While the data findings for this study were unexpected, the results contribute to the existing literature that describe the need for interventions among ELL students to help narrow the reading comprehension gap between English Language Learners and their English-speaking peers. A way of improving reading skills in ELL students with limited English proficiency is by having the students read more texts in class. Beginning level ELL students require guided support to help them develop interest and ability in reading more texts. More professional development ESL workshops are necessary for ESL instructors to learn additional strategies to teach the beginner level ESL students the college is serving. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]