Objective: The purpose of this study was to investigate grandmothers' verbal and nonverbal behaviors during young grandchildren-grandmother picture book reading. Methods: Participants were fifty-two children aged 22-42 months and their grandmothers. The researcher visited participating children’s homes or child care centers and videotaped grandchildren-grandmother book reading activities. Each grandmother read two picture books for each observation. Grandmother surveys were administered after the reading activities. Parent surveys were completed by parents and were returned to the researcher. Results: First, grandmothers began reading picture books to grandchildren when children were 6 to 11-months-old or 12 to 17-months-old. They spent 5 to 10 minutes or 10 to 15 minutes at a time reading books. Second, grandmothers' most frequent verbal behavior during young grandchildren-grandmother picture book reading was ‘explaining,’ followed by ‘questioning,’ and ‘providing feedback,’ in that order. Grandmothers' MLU-eojeol during grandchildren-grandmother reading was 2.56. Their most frequently used nonverbal behavior was ‘pointing,’ followed by ‘gestures.’ Lastly, there was a significant difference in grandmothers' verbal and nonverbal behaviors during grandchildren-grandmother reading, depending on the grandmothers’ characteristics. Conclusion/Implications: Grandmothers use various verbal and nonverbal behaviors during grandchildren-grandmother picture book reading activities, and there are significant differences in grandmothers' verbal and nonverbal behaviors with grandchildren based on grandmothers' characteristics.