The study focused on expanding the understanding of how parental mentalization (PM) occurs in an ecologically valid context during a toddler’s first transition phase from home care to early childhood education and care (ECEC). Little attention has been paid to under-standing how PM occurs during a potentially stressful period of life when preparing for the first experiences of separation between the parent and the toddler. The aim of this phenomenographic study was to distinguish the qualitatively different ways parents (n = 21) experi-ence, conceptualize, perceive, and understand the forthcoming first separation from their toddler (at 10–24 months). The results are pre-sented in the outcome space on the basis of the phenomenographic analysis, which consisted of three categories of description: the par-ent’s own experiences and orientation for the forthcoming separation phase, the parent’s representation of the child’s forthcoming experi-ences, and PM indicators. These categories contained 10 subcategories and 480 meaning units. The mentalization indicators provide a broad view of PM in the transition phase, which consists of tolerable and reflective uncertainty. This is where some core functions of PM may be observed, maintaining flexibility toward the reactions of parents them-selves and their toddlers.