The National Reading Panel identified phonemic awareness (PA) as one of the five components of reading and found explicit instruction effective in developing PA skills in students. In the current meta-analysis, we explored the extent to which PA instruction was effective for developing PA skills in preschool through first-grade students and examined moderators related to malleable instructional characteristics relevant to the effective implementation of PA instruction in schools (e.g., type of instructor, specifically including computer programs and parents aside from teachers as instructors) and their possible interactions. We collected data from 46 experimental and quasi-experimental primary studies, with 59 independent samples providing 119 effect sizes (treatment groups, N = 1892; control groups, N = 1747). Using robust variance estimation, PA instruction was moderately effective (g = 0.63, p < 0.001) at improving PA outcomes. No statistically significant difference was found for type of instructor. Other moderator analyses revealed no significant differences for group size, duration, PA skills taught, use of letters, grade level, at-risk for reading difficulties status, or English language learner status. Finally, examination of the interaction between type of instructor and at-risk status suggested teachers, computer programs, and parents are effective instructors for both at-risk and low-risk students. As schools plan for effective PA instruction, results indicate computer programs and parents can be useful resources to build PA skills for students to supplement teacher instruction.