Abstract: The subject disclosure is directed towards a technology in which a mobile device such as a phone automatically changes its lock wallpaper content (e.g., an image or video) that appears when the device is in its lock state. An API or the like allows information to be received from an application or service according to which the content is changed, including obtaining the content as needed. The lock wallpaper content may change in response to an automatic change event, and may correspond to a current device context. For example, lock wallpaper content may be displayed based upon a currently playing podcast, audio track, or currently running application program or service. The lock wallpaper may change among content obtained from a social networking site, or from a favorites store. The device may allow gesturing to change the content.