Research Findings: This study investigated early childhood education and care (ECEC) teachers' experiences of occupational well-being during a two-year pre-primary education trial in Finland. Profile groups of the trial experimental group teachers (n = 376) were identified. We also examined whether the identified profiles differed with respect to different ECEC classroom and teacher professional characteristics. Through latent profile analysis, three profile groups of occupational well-being were identified among the ECEC teachers: "empowered" (n = 34), "strained" (n = 138), and "stable teachers" (n = 200). In the majority of the pre-primary groups of empowered teachers, children represented the same age group, whereas the age distribution varied more among the pre-primary groups of strained and stable teachers. Empowered teachers reported having more instructed activity sessions and distributing responsibility more among the personnel teams. Strained teachers reported having more individual responsibility for instructing group activities. Practice or Policy: Attention to ECEC teachers' occupational well-being should be paid in dynamic and changing circumstances of their work careers, such as the Finnish two-year pre-primary education trial. Nationally unitary and appropriate classroom resources should be guaranteed to support ECEC teachers' well-being both in trials and in their everyday work.