Over 90% of hip fractures are due to falls. Yet, only 1-2% of falls result in hip fracture. This suggests that there exist factors that determine injurious and non-injurious falls, but we have limited information on this area. My PhD research addresses this issue through three related studies. My first study examined age-related changes in the dynamic compressive properties (stiffness and damping) of soft tissues over the hip region. My results indicate that the soft tissues of older adults absorb 70% less energy than those of young adults, thereby requiring more energy to be absorbed in the underlying skeletal components, with corresponding increase in fracture risk. My second study determined the effect of hip abductor muscle forces and knee boundary conditions on bone stress at the femoral neck during simulated falls. My results show that physiologically feasible increases in muscle force can reduce peak compressive and tensile stresses by up to 24 and 47%, respectively. These effects are similar to the magnitude of decline in fracture strength associated with osteoporosis. Therefore, muscle contraction at impact may be as important as bone density in determining hip fracture risk during a fall. My third study analyzed the kinematics of real-life falls in older adults, as captured by surveillance cameras, to estimate velocity of the pelvis at impact -- a primary determinant of impact force and fracture risk. Results show that the pelvis impact velocity averages 2.08 m/s, which is 48% below simple free-fall predictions based on fall height ((2gh)^0.5) and 20% below average previously reported for young adults. Results also show that several mechanisms contribute to reducing the pelvis impact velocity, including hand impact and attempts to recover balance by stepping. Collectively, these findings should add important pieces to the puzzle of whether a particular fall will result in hip fracture, and informs future direction for clinical and laboratory-based research on hip fracture prevention.