The PEAR Group occasionally publishes Administrative Documents, which describe the Group's decisions. You should read those documents before starting serious contributions to PEAR, because they contain important information about the inner workings of PEAR. The developers mailing list will be informed when new documents are added.
This manual contains the Developer Guide, which provides valuable information for using the tools of a PEAR developer.
The Coding Standards describe the standards which PEAR code must adhere to.