A method to be performed by a media playback system, the method comprising: determining that a particular playback device is a shared playback device that is available to be shared between a first bonded zone comprising a first playback device (504, 506, 508) and a second bonded zone comprising a second playback device (512, 513); determining that the shared playback device is a member of the first bonded zone; and implementing a change in bonded zone membership of the shared playback device to join the shared playback device to the second bonded zone; characterized in that implementing the change is performed according to one or more rules, without input from a controller (526, 528) for changing the bonded zone membership, wherein the one or more rules comprise at least one of: when the first bonded zone is presenting media or has presented media within a threshold time, the shared playback device joins or remains in the first bonded zone and does not join the second bonded zone; when the first bonded zone is not presenting media or has not presented media within a threshold amount of time and the second bonded zone is presenting media, the shared playback device joins the second bonded zone; and when the first and second bonded zones are simultaneously presenting media, the shared playback device one of: remains joined to the bonded zone to which it is currently joined; joins a preferred one of the first and second bonded zones based on a preference associated with the shared playback device that indicates which of the first and second bonded zones the shared playback device is to join when both the first and second bonded zones are presenting media; and joins both of the first and second bonded zones, when the media being simultaneously presented by both the first and second bonded zones is the same media. determining that a particular playback device is a shared playback device that is available to be shared between a first bonded zone comprising a first playback device (504, 506, 508) and a second bonded zone comprising a second playback device (512, 513); determining that the shared playback device is a member of the first bonded zone; and implementing a change in bonded zone membership of the shared playback device to join the shared playback device to the second bonded zone; characterized in that implementing the change is performed according to one or more rules, without input from a controller (526, 528) for changing the bonded zone membership, wherein the one or more rules comprise at least one of: when the first bonded zone is presenting media or has presented media within a threshold time, the shared playback device joins or remains in the first bonded zone and does not join the second bonded zone; when the first bonded zone is not presenting media or has not presented media within a threshold amount of time and the second bonded zone is presenting media, the shared playback device joins the second bonded zone; and when the first and second bonded zones are simultaneously presenting media, the shared playback device one of: remains joined to the bonded zone to which it is currently joined; joins a preferred one of the first and second bonded zones based on a preference associated with the shared playback device that indicates which of the first and second bonded zones the shared playback device is to join when both the first and second bonded zones are presenting media; and joins both of the first and second bonded zones, when the media being simultaneously presented by both the first and second bonded zones is the same media. when the first bonded zone is presenting media or has presented media within a threshold time, the shared playback device joins or remains in the first bonded zone and does not join the second bonded zone; when the first bonded zone is not presenting media or has not presented media within a threshold amount of time and the second bonded zone is presenting media, the shared playback device joins the second bonded zone; and when the first and second bonded zones are simultaneously presenting media, the shared playback device one of: remains joined to the bonded zone to which it is currently joined; joins a preferred one of the first and second bonded zones based on a preference associated with the shared playback device that indicates which of the first and second bonded zones the shared playback device is to join when both the first and second bonded zones are presenting media; and joins both of the first and second bonded zones, when the media being simultaneously presented by both the first and second bonded zones is the same media. remains joined to the bonded zone to which it is currently joined; joins a preferred one of the first and second bonded zones based on a preference associated with the shared playback device that indicates which of the first and second bonded zones the shared playback device is to join when both the first and second bonded zones are presenting media; and joins both of the first and second bonded zones, when the media being simultaneously presented by both the first and second bonded zones is the same media.