Start here: Really general overview: This is a good overview of the specifications: Here are some of the standards we'll be implementing. Note that several of these documents are referenced in our target spec: Overview of the specification dependencies and documents: Google's instructions on using Sunbird (free/open source calendar software that supports CalDAV as a client) with Google Calendar: This is a document that outlines the coding standards that will be in effect on all software we write: Code resources for CalDAV and GroupDAV: caldav: groupdav: DavMail: (CalDav Gateway with Exchange)