The article describes a partnership between two of the libraries at the University of California, San Diego (UCSD) through which two staff in one library worked part-time at the other during the summer of 2006 in order to maximize staffing efficiency among the units, as well as to realize professional development-related goals for the staff involved. The author outlines challenges faced by the project's coordinators, outcomes for the two UCSD libraries, and recommendations for other libraries experimenting with similar staff rotation projects.