The most current official racquetball rulebook (pdf file) can be downloaded from the teamusa.org website or from this link: Downloadable/Printable Rulebook-2013 Version (September 2013).
There are 4 new rule changes in this version:
1. In USAR-sanctioned events throughout the nation, all divisions (including the “Open” divisions) will play the two-serve game — except for the U.S. National Team Qualifying divisions at the U.S. National Doubles and the U.S. National Singles Championships. See Rules 3.1 and 5.
2. Players must wear shoes and cannot play in socks only or in bare feet. See Rule 2.5(b).
3. Electronic audio devices cannot be worn during play unless they are needed to amplify one’s hearing ability. See Rule 2.5(c).
4. Unintentional “carries” during the rally are allowed and are no longer called. See Rule 3.13(b).