The grandparent role has been often described as one of the most fulfilling aspects of older age. Yet, no longitudinal studies investigated the effect of the transition to grandparenthood on older adults' sense of purpose and meaning in life. In this pre-registered study, we investigated the effect of becoming a first-time grandparent and a first-time caregiving grandparent on changes in sense of purpose and meaning in life. We used data from the Health and Retirement Study (HRS) and English Longitudinal Study of Ageing (ELSA), covering up to 12 years around the transition (N HRS = 843, N ELSA = 587). To disentangle potential grandparenthood effects from age-related developmental changes, we used propensity score matching to compare grandparents to matched non-grandparents. Using latent change score models, we only found increases in sense of purpose in the years leading up to the transition, but not afterwards. No consistent findings of mean-level changes were observed in the control groups. Thus, our findings suggest that becoming a (caregiving) grandparent does not necessarily contribute to higher meaning and sense of purpose in life than before or compared to non-grandparents. Older adults often report that being a grandparent is one of the most fulfilling roles of older age. However, there are no studies to investigate how older adults' sense of purpose and meaning in life changes over time when they first become grandparents. Similarly, no past research has investigated how the two constructs change when first-time grandparents start to provide care for their grandchildren for the first time. In this study, we use data from two large population studies (Health and Retirement Study and English Longitudinal Study of Ageing; NHRS = 843, NELSA = 587 ) covering up to 12 years to see if newly grandparents increase in sense of purpose and meaning in life during the transition to (active) grandparenthood. To make sure that any potential effects are not due to life events or changes that normally take place during old age, we compared grandparents to older adults that were not (yet) grandparents, or did not have children, but were similar to our target group (i.e., grandparents) with respect to other characteristics-for example, age, gender, and health status. We did not find evidence for any change in sense of purpose and meaning in life after older adults become grandparents, but only in the years leading up to the transition to grandparenthood. For the groups of non-grandparents, we did not find any notable differences in how sense of purpose and meaning in life changed during the study period compared to the groups of grandparents. Starting to provide grandchildren as a first-time grandparent also did not lead to any changes in sense of purpose and meaning in life.