In this paper, we identified key terms and latent topics in posts on online forums, called “online cafés” in Korea. We analyzed 41,699 online posts that mentioned at least one of the 70 Korean terms related to “child care” as well as one of the 67 terms related to “grandparents”. The data were posted online between 2016 and 2019 on Naver and Daum, two leading portal sites in Korea. Using topic modeling with Latent Dirichlet Allocation (LDA), we selected and named 16 topics, and then grouped them into four themes. The first theme was “grandparents and grandchildren,” which included four topics: grandparent-grandchild relationships (T1), the everyday lives of adult children and grandchildren (T2), the roles of parents and grandparents (T3), and grandparent’s leisure time (T4). The second theme was “care in early childhood” with four topics: birth order and number of children (T5), childꠓbirth and postnatal care (T6), infant child care (T7), and attachment (T8). The third theme was “child care and support for parents” with four topics: work and child care (T9), day care and kindergarten (T10), parenting information (T11), and parenting education and counseling (T12). The last theme was “marriage and gender roles” with four topics: marital life (T13), “dok-bak-yuk-ah” (parenting solo) (T14), in-laws (T15), and divorce (T16). Our results highlight that online discussions about grandparents include a variety of topics in the context of child care, suggesting that grandparents are not only child care providers but are also actively involved in the everyday lives of their adult children and grandchildren.