The eXtensible Imaging Platform (XIP™) consists of a set of tools for rapidly developing medical imaging processing and visualization applications. The XIP Wiki site, accessible from http://www.openxip.org, describes the tools in more detail. One of the goals for XIP within the caBIG^® In Vivo Imaging program is to allow cancer researchers to easily create complex data analysis programs (e.g. lesion change detection) targeted at specific investigations. By employing the coming DICOM WG-23 Application Hosting interfaces, XIP Applications can be distributed to a variety of installations, thus providing some consistency in data collection for clinical trials. Of course, the XIP tools can also be employed to create other types of applications.