Synchronization architectures, methods, systems, and computer readable media are described. One exemplary embodiment includes a first software component which is configured to cause retrieval and storage of structured data for a first data class from a first store of the structured data on a device, such as a first data processing system, and is configured to synchronize structured data for the first data class in the first store with structured data of the first data class in a second store on a host, such as a second data processing system. The first software component is separate from an application software which provides a user interface to allow a user to access and edit the structured data. The first software component synchronizes the structured data through a second software component which interfaces with the host and the device and which controls an order of synchronizing and a plurality of data classes including the first data class.