In an exploratory, intensive case study, we investigated the well-being of young children (0-4 years) with a time-sampling design. The total sample included 940 individual observations for 30 children during four consecutive weeks. Data collection involved external coding of videotaped episodes and caregiver- and parent-reported measures. Well-being was, on average, neutral for most children, but fluctuated significantly throughout the day. The level of well-being was higher during free play and caregiver-led activities, compared to lunch/snack and transitions during the program. Conflicts with other children were related to lower levels of well-being. Elder children had higher levels of well-being. We discuss implications for future research and practice to increase children's well-being in early childhood education and care.