Early literacy skills are critical for success in school, yet many children fail to obtain these skills in a timely manner leaving them unable to perform at minimal academic expectations. The purpose of this study was to examine the effects of word box instruction, a research-based intervention designed to promote phonemic awareness, on the phonological, reading, and spelling skills of three kindergartners. A multiple probe design across the three skills was sequentially replicated across students to determine the effectiveness of the intervention. Results demonstrated a functional relation between the word box instruction and increases in all three students' segmenting skills and letter-sound correspondences, along with demonstrated improvements in spelling and reading.