Although sensory input is continuous, we perceive and remember discrete events. Event segmentation has been studied extensively in adults, but little is known about how the youngest minds experience the world. The main impediment to studying event segmentation in infants has been a reliance on explicit parsing tasks that are not possible at this age. fMRI has recently proven successful at measuring adult event segmentation during task-free, naturalistic perception. Applied to infants, this could reveal the nature of their event segmentation, from low-level sensory transients to high-level cognitive boundaries. We collected fMRI data from 25 adults and 25 infants less than one year of age watching the same short movie. Neural events were defined by the stability of voxel activity patterns. In adults, we replicated a hierarchical gradient of event timescales, from shorter events in early visual regions to longer events in later visual and narrative regions. In infants, however, longer events were found throughout the brain, including in a second dataset. Infant event structure fit adult data and vice versa, but adult behavioral boundaries were differently expressed in adult and infant brains. These findings have implications for the nature of infant experience and cognition.