DIF analyses can and indeed should be used to ensure that assessment items and tests are fair, in particular equally valid for various specified examinee subgroups, such as males and females. The DIF-Pack includes both source code and executable code for SIBTEST, POLY-SIBTEST, and Crossing SIBTEST, which together can test variously scored items and bundles of items (a bundle viewed as a collection) for various kinds of DIF. The source code is provided to facilitate continued improvement of the software, including applications to non-standard settings, research projects, improvements to the statistical algorithms, etc.