In order to study the functions and activities of chromatin remodeling enzymes in vitro, it is necessary to be able to reconstitute nucleosomes on DNA templates. In this chapter, we describe procedures for purification of histones from E. coli, formation of octamers, and reconstitution of nucleosomes, which can be further modified by chromatin modifiers. In addition, we describe methods to purify nucleosomes from human cells. Finally, we also describe assays to test binding and remodeling activities of chromatin remodelers.