Falls are the number one cause of unintentional injury. Any fall may cause an injury, but even in older adults, fewer than 5% of falls cause injuries treated in hospitals. These trends may be explained, in part, by the role of "fall-protective" responses, such as upper limbs bracing, in allowing humans to avoid injury. Presumably these responses are shaped to the situational and environmental context of the fall. In this thesis, I analyzed video footage of real-life falls in older adults, to improve our understanding on how older adults interact with environmental features during falls, and how human-environmental interactions affect risk for injury. From video analysis of 1759 falls by older adults, I found that 60% of falls resulted in contact of body parts with objects other than the ground after fall initiation (Chapter 2). The probability of hand contacts to objects was highest in forward falls, while head and torso contacts to objects were more common in backward and sideways falls. These trends may reflect the influence of being able to visualize and adjust one's falling patterns to nearby objects. The odds for head injury were reduced in falls where older adults held or successfully grasped objects (Chapter 3). The odds for head injury were greater in falls where the head impacted the floor (versus an object). From laboratory-based falling experiments with young adults, I found that Kinovea digitization of 30 Hz standard video was accurate to within 10% in estimating body segment kinematics during falls, when compared with 3D motion capture (Chapter 4). From digitizing forward falls in older adults involving attempts to brace the fall with the upper limbs (Chapter 5), I found that, when compared to falls where head impact was avoided, falls that resulted in head impact differed in arm configuration after landing, but not in body positions and velocities at the instant of landing. By generating new evidence on how injury risk in falls depends on environmental features, and human-environmental interactions, my results have important implications for the development of safe movement environments and training programs to reduce fall-related injuries in older adults.