In the present review we summarize different strategies to induce DNA compaction and decompaction. DNA compaction is achieved using different cationic co-solutes, such as trivalent ions, surfactant, and polycations. In addition, single-chained DNA compaction can also be achieved in solvents with low dielectric constants and by confinement. The decompaction strategies depend, naturally, on the method used for the compaction and can be accomplished by, for example, heparins, cyclodextrins, non-ionic or anionic surfactants.