Rajni Hatti-Kaul and her expert coauthors combine theory, methodology, and applications in a practical collection of easily reproducible protocols for bioseparations in aqueous two-phase systems (ATPS). The protocols range from established methods to cutting-edge techniques with potential biotechnological applications. Among the methods detailed are those for ATPS preparation and characterization, for partitioning applied to soluble molecules and particulates (including whole cells, membranes, and organelles), and for the isolation and purification of proteins - including a glimpse of large-scale handling of two-phase separations. Practical and informative, with its detailed guidelines allowing researchers to adapt specific systems to their own separation needs, Aqueous Two-Phase Systems: Methods and Protocols demonstrates the scope and utility of two-phase aqueous systems in both basic and applied research.