Two field experiments tested the hypothesis that a bystander's increased responsibility to act increases the likelihood of his helping the victim of an emergency. In Experiment 1, an individual asked or did not ask the bystander to protect his property in his absence. In Experiment 2, the presence/absence of an unattentive confederate was varied orthogonally to the request/no request manipulation. The results of both experiments indicated that bystanders who received a prior request for protective assistance felt more personally responsible for protecting the individual's property and were more likely to prevent a theft of that property than were bystanders who received no request. The presence of a confederate in Experiment 2 decreased bystanders' felt responsibility and their willingness to intervene on the victim's behalf. The results were interpreted as support for the “felt responsibility” proposition of the Latané and Darley (1970) model of bystander intervention.