Falls cause more than 95% of hip fractures and 65% of head injuries in older adults. A major barrier to prevention is lack of objective evidence of the circumstances of falls, especially in the high-risk long-term care (LTC) setting. My PhD research addresses this issue through the analysis of falls captured on video in two LTC facilities. My first study involved the development and validation of a 24-item video analysis questionnaire that probes key biomechanical aspects of fall initiation, descent, and impact from video footage. My results demonstrated good inter-rater and intra-rater reliability in 17 of the 24 questions (agreement≥80%, kappa≥0.6). My second study compared the circumstances of falls described in incident reports to information from video analysis (n=309, with 863 falls). I found poor agreement on the cause of imbalance and activity at time of fall (agreement=45%, kappa≤0.25), and moderate agreement on the use of mobility aids (agreement=79.5%, kappa=0.59). My third study examined how risk of head impact during falls was associated with biomechanical factors (from video analysis) and physiological factors (from Minimum Data Set) (n=160, with 520 falls). I found that 33% of falls involved head impact. Odds for head impact were increased more than 2- fold for female, impaired vision, and intact cognition. These trends were explained in part by women and individuals with relatively intact cognition who tend to fall during walking and fall forward (both increased the odds for head impact). Odds for head impact were not reduced by hand impact. Body rotation during descent from forward to sideways or backward decreased the odds of head impact nearly 3-fold. My fourth study used the same data set to examine how risk of hip impact during falls was influenced by biomechanical and physiological factors. I found falling forward was just as likely as falling sideways to cause hip impact. There was no association between physiological factors and odds for hip impact. Collectively, my findings should help guide the development of improved fall and injury prevention strategies, by providing new evidence on the circumstances of falls in LTC, and the risk factors for impact to the head and hip.