Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for fall detection using data for a person's shadow. One of the methods includes obtaining, from a camera, an image of a portion of a property; determining whether a shadow is likely depicted in the image; in response to determining that a shadow is likely depicted in the image, determining whether the shadow in the image likely represents a potentially falling person; and in response to determining that the shadow in the image likely represents a potentially falling person, performing one or more actions for the potentially falling person.