The double helix of the oligoresorcinol nonamer formed in water was unwound by beta-cyclodextrin (beta-CD), and the resulting single strands of the nonamer threaded the beta-CD to form a twisted [3]-pseudorotaxane with a controlled helicity. Upon the addition of an adamantane, the single strand of the oligoresorcinol nonamer was expelled out of the beta-CD wheels, thus regenerating the double helix. This supramolecularly controlled, reversible unwinding and rewinding of the double helix is unique and can be readily monitored by spectroscopic techniques.