We present applications of partial-update adaptive signal processing to acoustic/network echo cancellation, blind fractionally spaced channel equalization, and blind adaptive linear multiuser detection. These are not the only application areas for partial-update adaptive signal processing. Any adaptive signal processing problem can potentially benefit from partial coefficient updates in terms of computational complexity reduction. It is also possible for partial-update adaptive filters to achieve performance improvement at reduced complexity. In this chapter we will demonstrate performance improvements achieved by selective partial updates in blind channel equalization and linear multiuser detection. ...