Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for peer-to-peer device activation. In one aspect, a method includes receiving, at a first user device associated with a first user account, an invitation to claim a second user device. Accepting, by the first user device, the invitation to claim the second user device. In response to accepting the invitation to claim the second device, sending a request for a registration token that includes a unique identifier for the second user device and associated with the first user account. Receiving, in response to the request, the registration token over the second communication protocol. Transmitting, from the first user device to the second user device, the registration token, wherein the registration token, upon receipt by the second user device, is used by the second user device to associate the second user device with the first user account.